Is a dominant trait in a parent always reflected in all children?

Answer

To understand this properly, it is important to know that you carry two copies of each gene: one you inherited from your mother, the other from your father. For most traits it is not the case that one gene determines the trait, there are almost always several to very many genes involved in a trait. But for the sake of simplicity, let’s assume a trait that is determined by one gene.

For a dominant trait it is enough that one of your two genes is “positive”. For example, you inherit that dominant trait from your mother; your father gave you a “negative” gene. But beware: your mother also has two genes for that characteristic, and she only passes one on to each of her children. If she carries a “positive” and a “negative” gene, then (statistically speaking) she will pass on the positive to half of her children, the negative to the other half. Which gene she passes on is completely coincidental. It is therefore also possible that she will not pass it on to any of her children, or to all of them… With each child there is a one in two chance that he or she will inherit the characteristic.

It is also possible that your mother carries two “positive” genes, so that she has inherited the trait from both her parents. In that case, all her children will inherit the trait.