A woman without dimples married man who had dimples and who is known to be heterozygous. What is chance of first child will have dimples?

To determine the chance of the first child having dimples, we need to consider the genetic inheritance of dimples. Dimples are generally considered to be a dominant trait, meaning that if an individual has at least one copy of the gene for dimples, they will have dimples.

Given that the man is heterozygous for dimples, it means that he has one copy of the gene for dimples (D) and one copy of the gene for no dimples (d). The woman, on the other hand, does not have any dimples, so she would be homozygous for no dimples (dd).

When these two individuals have a child, each parent will randomly pass on one copy of their gene to the child. Therefore, there are four possible combinations of genes that the child can inherit: DD, Dd, dD, or dd.

Out of these four combinations, three of them (DD, Dd, and dD) would result in the child having dimples, while only one combination (dd) would result in the child not having dimples.

Therefore, the chance of the first child having dimples is 3 out of 4, or 75%.