The main aim of this study is to test the hypothesis that females gain genetic benefits for their offspring through mate choice. Whilst it is known from work on non-human animals that mate choice can result in improved growth and survival of offspring (e.g. Petrie 1994) the possibility that human mate choice can affect subsequent fitness-related traits of children has not been investigated. We aim to specifically test this possibility using data collected for the ALSPAC study.

If females are gaining genetic benefits for their offspring from mate choice we can predict that disruption of the mate choice process will result in a lack of genetic benefits and thus poorer offspring growth and health. It is known that from the laboratory that use of the contraceptive pill at the time of mate choice can result in the alteration of female mate preferences such that females are more likely to prefer individuals that are more Mhc similar to themselves (Roberts et al 2008; Alvergne & Lummaa 2010). Mhc similarity between biological parents can lower the degree of heterozygosity at the Mhc in children such that they are less able to combat disease. We would like to test whether such mate choice disruption has any real world consequences. We aim to do this by:-

1) comparing health of children for a sample of women who chose their biological fathers whilst taking the pill with that of a sample of women who intitiated oral contraceptive use after meeting the biological fathers of their children.

2) comparing the degree of MhC similarity between mothers and fathers in a group of women who met their partners whilst using oral contraceptives with another group of women who started using oral contraception after making their mate choice.

3) comparing the degree of heterozygosity at the Mhc in the children of mothers who chose their partners whilst on the pill with those from mothers who did not.