Question

if both parents have dimples then is it true that the child will definitely have dimples?

Answer 1

Dimples are highly heritable, meaning that people who have dimples tend to have children with dimples—but not always. Because their inheritance isn't completely predictable, dimples are considered an “irregular” dominant trait. Having dimples is probably controlled mainly by one gene but also influenced by other genes.

Each parent provides one of these genes to the child. So, if both the parents have dimples, the children have 50-100% chances of inheriting dimple genes. If, however, only one parent has dimple genes, the chances of the children inheriting the genes are 50%.