Excessive methylation of the embryo's genome during development in the womb leads to too many genes being turned off. This over-methylation may be caused by the child receiving identical copies of the same methylation control gene from both parents. When the copies are identical (a.k.a. homozygous), they are expressed too strongly in the embryo. Fortunately (and unfortunately), methylation is affected by the behavior and diet of the parents. This means that if consanguineous parents change their diet, they can improve the health of their future children.
More research has come out about methylation and diet. The study focused on children of impoverished parents, but less methylation is exactly what the children of consanguineous parents need. They found that two compounds - cysteine and homocysteine - were highly correlated with lower levels of methylation in offspring. Homocysteine and it's precursors are dangerous for personal health in high levels, but cysteine is important in many processes (like reducing heavy metals in your blood).
Cysteine can be found in these foods:
- red peppers
- brussels sprouts
- wheat germ
- sprouted lentils