Can I pass milk allergy on to my kids?

As you might already know each one of us was made by our mother and father. On conception, the chromosomes of both our parents fused together and half the genes of each parent combined to make what you and I are today. Each human being has 46 chromosomes in our blood cell (not in the red cells though). Each chromosome contains about 1000 genes and each gene has a particular function to do.

For instance if you have a black skin then the gene that produces the protein melanin is switched on. If you are a Mediterranean and have a tan skin then the same gene is producing less melanin, hence the lighter colour in Mediterrenians than in black people. Moreover, Nordics have even a lighter skin and as you can predict the gene responsible for the production of melanin produces less melanin. Genes can become damaged during conception or during pregnancy and this damage can hinder and alter their production of the protein they are assigned to produce. In very rare cases (but they exist) the mutation or damage to the gene can completely disallow the gene to function at all and therefore produces no proteins - in genetics it is called switching off (see below). Staying on the case of skin colour albinos are the result of the damaged gene that produces melanin.

Similarly, everybody has 2 genes (in each cell) that produce lactase (to breakdown lactose). One is inherited from the father and one from the mother. If one of the genes we inherited does not switch on properly when it should do, there will not be enough lactase produced, however, this is not a big problem because the other gene normally compensates by producing more lactase. In this case the person in question would not suffer from any intolerance. Now if this person has a child and passes the weak gene to the child and the mother happens to have a weak gene similar to the partner, then the child is going to inherit two weak genes that are not able to produce enough lactase, hence the lactose intolerance to the child while the parents are not suffering.

The extent of how much intolerant to lactose the read more