Da Wikia:
Mutants may be born to human or mutant parents, though the odds of a mutant birth are much better for the latter. Likewise, it is rare but possible for mutant parents to have human children, termed "baseline" by characters within the Marvel Universe. Some baseline humans are genetically predisposed towards having mutant descendants such as the Guthrie family (see Cannonball, Husk, and Icarus). Mutant children born to mutant parent(s) will not necessarily have the same power(s) as their parent(s), nor will they necessarily have the same power(s) as any mutant siblings they may have; however, examples of children with the same power(s) as their parents and/or siblings are not uncommon.