Why is it that family members and friend groups all have different types?

Ok, I can confirm for nuclear family only, and not necessarily friend groups…. if you have, say an ESTP, they may have more than one close ISTP friend, but those ISTPs probably don’t consider each other that close, in turn, even if they sometimes hang out as part of a wider group of friends.

And the answer is… I have no idea!  Nature likes diversity?  Nuture means you’re a reflection and a product of the people around you?

I can tell you that the most common pattern that happens is if you have, say, ESTJ and ENFP parents, the first child is one letter away from one parent – say, an ESTP.  The second child is one letter away from the second parent – say, an ENTP.  Any other children tend to be a letter away from a sibling.  Maybe an ISTP or an INTP.  It doesn’t always work this way, but often enough so as to be noticeable.

Hey. In your opinion what are some differences that you may have noticed between thinker girls and thinkers boys and feeler girls and feeler boys

In a word: socialization.

I don’t really know how to answer this more specifically (or more generally tbh), because it depends entirely on cultural/institutional values + personal/family values and how the expectations of how you should behave according to those values clashes or agrees with you as a person.

I don’t think I would be comfortable pointing to differences and saying the reason for them is gender without considering the intersection of a great many other factors.  Sounds like an interesting graduate thesis for an enterprising academic, though.