As mentioned in another answer, it is kind of complicated.
Many of the traits associated with effective witchcraft are hereditary. Some even correspond to other “marks” or in-born traits, even some that some people would class as defects. In my (the Dean’s) hometown’s local lore, bad eyesight was a sign that someone likely had the “second sight”, or super-deductive reasoning talent.
Sometimes though, differences are classed as signs of hereditary witch signs or marks because of ableism in a culture or perhaps a way to counter ableism by reminding people that everyone who is given a chance and has a benevolent nature can contribute something to a society. The problem of course is that much like racism, even “positive” ableism can be oppressive or dismissive of the individual. A person being forced or even just pressured too much into a role or occupation despite their desires and other capabilities is bad.
So yes, there are families for whom witchcraft or some type of spiritual service is kind of the family business. Yes there are people who are born with abilities out of the ordinary, and raised to use their talents effectively, but this doesn’t really make them more or less witches than anyone else with the same talent who put in the same work. Heredity is not what makes a good witch. Having supportive family sure does help a lot though.