The sibling variables

6.2.1 Deriving my own variables or using the derived variable variables

The MCS has a range of derived variables in the data sets provided to researchers, some of which relate to family structure and can be used to impute the central measures of family complexity (Rosenberg, 2012); however I have chosen to derive my own measures of sibling complexity direct from the household grid for reasons outlined below.

Each of the MCS waves come with a range of derived variables including some which indicate the siblings of the focal child in the household, from which the structure of the sibling relationship in the child’s household can be broadly determined. By cross referencing to the relationship between the respondents and siblings in the household about the relationship between members of the child’s household can be derived. There are distinct limitations to this method of deriving the relationship between household members.

The derived variables only use information about the relationship between family members and the cohort member – dhcrel. This ignores relevant information contained in the cohort member’s row in the columns which record the relationship between individuals and other household members. Deriving sibling composition using the full range of data allows a number of inconsistencies in the relationships between family members and the cohort member to be distinguished, and this implies that families may be different – in many cases more complex – than would otherwise have been apparent from just using the data which relates cohort members to household members.

In addition to the problems with the structure of the derived variables about the sibling structure of the cohort members household there is also relevant information contained in the parent interview about siblings and parents who live elsewhere which is not included in any of the derived variables, most importantly in identifying the number of non-shared parents that half siblings have.

6.2.2 Using the household grid to create a measure of sibling complexity

The household grid records the composition of cohort households and is collected from the main respondent during the main interview and is presented to researchers as a separate data file from the main interview data (Hansen, 2012). The household grid contains

128 demographic information about members of the cohort household, together with information about the relationships between household members. The household grid in the MCS is unusual among such grids in that it records all the bilateral relationships between household members rather than just relating the household members to a reference person as is common in most household based surveys. This enables a full set of relationships to be derived.

6.2.3 Typology of sibling relationships

The siblings living with the cohort member at wave four are used to create a typology of sibling relationships, once the relative age and shared parents of siblings are taken into account there are 82 different combinations of sibling relationships shared by the cohort members. Once similar categories are reduced, this gives a typology of 16 different types of sibling relationship.

The ambiguous case category includes those cohort members who live in households categorised by the contradictions in triangulated relationships outlined above. The missing information category includes households in which information about the parentage or age of siblings is missing. For analysis I will collapse the missing and ambiguous groups together, and whilst there are good reasons for viewing the remaining categories as distinct from each other, once other relevant dimensions of family complexity are included it may be necessary to create a heterogeneous ‘other ‘grouping to maintain the integrity of analysis. The frequency of each sibling group is shown in Table 9.

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TABLE 9:SIBLING GROUP COMPOSITION FOR ALL CHILDREN

CM's sibling relationship Freq. Percent Cum.

Ambiguous case 329 2.37 2.37

No full half or step siblings 1,862 13.44 15.81

Older full siblings only 4,332 31.26 47.07

Younger full siblings only 3,646 26.31 73.39

Older and younger full siblings only 1,804 13.02 86.40 Older maternal half siblings from one previous

partnership

1,106 7.98 94.39

Older paternal half siblings from one previous partnership

85 0.61 95.00

Half siblings adopted by the CM’s natural parent 20 0.14 95.14 Older maternal and paternal half siblings from

one previous partnership respectively

22 0.16 95.30

Younger maternal half siblings from one subsequent partnership

418 3.02 98.32

Younger paternal half siblings from one subsequent partnership

8 0.06 98.38

Older maternal half siblings from multiple previous partnerships

69 0.50 98.87

Younger maternal half siblings from multiple subsequent partnerships

22 0.16 99.03

Older and younger maternal half sibling from multiple partnerships

79 0.57 99.60

Full and step siblings 16 0.12 99.72

Step siblings only 9 0.06 99.78

Missing information 30 0.22 100.00

Total 13,857 100

6.2.4 The simplified sibling variable

The range of sibling relationships present amongst the MCS children is large, and not all the categories are large enough to meaningfully analyse. The sibling measure therefore needs to be simplified for analysis but without losing any of the important aspects of family

130 complexity. There are two important aspects of sibling groups which are difficult to establish and as such are not well studied; namely those sibling groups in which the shared parent has had children with at least three partners, and also if the relationships between family members are congruent with each other. Turning firstly to families in which the half siblings to the focal child are half siblings to each other, indicating that the parent in common has had children in more than two partnerships, the detail in the MCS household grid indicates if the focal child’s sibling group includes children from multiple non shared parents. By using the household grid to derive the sibling relationship it was possible to cross check relationships between individuals in the household, so where if A was a full sibling of the cohort child and B the step parent of the cohort child, B should be a step parent of A. In some cases this was not the case, as for example B was shown as biological parent of A. In these cases it is impossible to establish the relationship between household members so these children are assigned to the unknown sibling group. In Table 9 this is the group called ambiguous with 329 cases. Ambiguity of relationships between household members will be much more likely in the most complex sibling groups and thus these groups are probably undercounted to some extent.

The simplified measure classifies families by the most complex aspects of their sibling relationship, so all those children with half siblings with multiple non shared parents are categorised together regardless of the relative age of these siblings and the presence of any full siblings in the family. Children with half siblings with only one non shared parent are categorised by their relative age to the MCS child, and any full siblings are ignored. The simple sibling groups are unchanged from the full typology of the MCS data. Table 10 shows the distribution of the measure of simplified sibling group structure.

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TABLE 10:SIMPLIFIED SIBLING GROUP FOR ALL CHILDREN

Sibling group type Percent Cum.

No full, half or step siblings 1,862 13.44 13.44

Older full siblings only 4,332 31.26 44.7

Younger full siblings only 3,646 26.31 71.01

Older and younger full siblings only 1,804 13.02 84.03

Older maternal half siblings 1,126 8.13 92.16

Younger maternal half siblings 418 3.02 95.17

Half siblings with multiple non shared parents 170 1.23 96.4

Other 140 1.01 97.41

Unknown 359 2.59 100

Total 13,857 100

6.2.5 Limitations of the sibling group variables

The sibling group variable has two relatively small groups, namely the maternal half siblings with multiple non shared parents and the other siblings group. The maternal half siblings with multiple non shared parents includes children who have older, younger and both older and younger half siblings, but all these children have mothers who have had children with at least three partners. The other group is far more heterogeneous than any of the other groups including as it does those children with older paternal half siblings, younger paternal half siblings, older paternal and maternal half siblings, full and step siblings, and step siblings only.

The siblings are almost entirely maternal siblings because the methodology for looking at siblings used only those siblings who were present in the household with the cohort child at the age of seven. Only looking at co-resident siblings tips the balance in favour of maternal half siblings and to some extent towards younger siblings. The vast majority of young children live primarily with their mothers (calculations not shown), and if assume that most siblings live with their mothers maternal half siblings are likely to be visible when using the household grid. Children who are older and may have left home or are living with family members other than their mothers are less visible. Paternal half siblings are relatively rare, partly because when these are younger than the focal child the focal child is more likely to be living with their (presumably separated) mother, and where these are older the half siblings are likely to be living apart from their shared father.

132 Creating family complexity variables which are only a measure of maternal half siblings is in part a reflection of which aspects of the sibling relationship that is anticipated as being important and in part a pragmatic decision to the difficulty in locating paternal half siblings. Sibling relationships are based on growing up in a shared environment rather than a biological connection, for example children who were conceived using the same donor’s gametes are not considered a sibling group, whereas children adopted by the same adoptive parent(s) are. Looking at the sibling groups who are defined by their shared environment it might seem contradictory to define children in terms of their parentage however it is children’s relationship with their parents which is represented by the precise degree of their sibling relationship and this is what I wish to examine. So where children have non shared parents this seems likely to affect both their relationship with their shared parent, their non-shared parent and their social parent (conventionally the non-shared biological parent of the younger child would be considered a social parent of the older child whereas there would not be a relationship between the younger child and the non-shared biological parent of the older child). Having children with multiple partners may also affect the capacity of the shared parent to parent the children through the difficulties of managing their relationships and joint parenting with multiple partners. When children have half siblings who live outside of the same household these are not recorded in the household grid; although the main respondent is asked about any children living elsewhere in the main this applies to biological mothers who are overwhelmingly likely to have their children living with them. There is no information about the children of non-resident biological parents, even when children spend substantial amounts of time with the non- resident parent. These reservations have made it necessary to restrict the analysis to those siblings recorded as living with the focal child when the focal child is aged seven as these are the children with whom the focal child will have most contact with on a daily basis. The sibling group measure is analysed as a categorical variable, and as there is no obvious normative sibling group the no full, half or step sibling group has been selected as the reference group. All of the outcome variables are binary measures so logistic models reporting the odds of a group experiencing a poor outcome relative to the reference model are reported.

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