I think there is a genetic component but I would suggest looking at functions not MBTI letters. It's also likely very complex.
Anyways:
mom's mom: enfp ne, fi, te
mom's dad: extp xe, ti,fe
mom: enfp ne,fi,te
dad's mom: infj ni, fe,ti
dad's dad: unknown
dad: infj ni,fe,ti
me: enfp ne,fi,te
sister: esfp se,fi,te
half brothers dad: extp Xe,fe, Ti
half brother: esfp se, fi, te
so in my family, XeFiTe is the only consistent thread which constantly gets passed in preference over the TiFe/FeTi combo?? However we dont have Si popping up out of nowhere. We also dont have IXXPs either or Fe doms popping up either...
ex-dad-in-law: intj ni, te, fi
(his mom:estp, his dad: ixtp)
ex-mom-in-law: istp ti, se,ni,fe
(her mom: enfp, her dad: istp)
my ex-husband :istp ti,se, ni,fe
sis-in-law 1:enfp ne,fi,te
sis-in-law 2:estp se,ti,fe
so in my husbands family, mom's type and the two grandmom's types carried over. However notice you dont have Fe doms popping up out of nowhere...
my son1:enfp
my son2: IXTJ-likely an intj
my mom's mom was an enfp so we carry the tradition on it seems.
my second son seems to have carried over grandpa's type.
my sister-an esfp has two kids
kid 1 with an esfp is an esfp
kid 2 with an estp is an enfj-however dad's mom was an enfj.
my sister law, the estp has a kid with an esfj. haha, they had an estj kid
so se,ti, fe plus fe,si,ne equals te, si, ne. like mom was carrying a recessive te from her dad?
this would be so much more straightforward if everyone had like fourteen kids...