I will put a complaint about all the anecdotal evidence in this thread. That is not what the general questions forum is supposed to be about.
It is totally useless in regard to answering the OPs question in a meaningful way. Yet it clutters the thread, and might confuse people who think it has some importance.
And that’s why anecdotal evidence is so bad. If we start with thousands of people, 1 in 1024 will have 10 heads. The others don’t care, but the 1 in 1024 may claim to have a special “heads flipping” power.
If we only met 1 such person, we’d be tempted to believe the coin was unfair or that there may be something to the “super” power. But if we found out there was an experiment involving thousands, we’d be less sanguine. After all, the ones who flipped tails along the way don’t care enough to say “hey, I didn’t flip heads 10 times in a row, look how special I am”.
Families are the same. This isn’t a special family (1 guy who’s flipped 10 heads in a row solo) that’s been discovered but one that’s taken out of the context of hundreds of millions around the world (among the “1 of 1024” who managed it).
I’d still put more credence into the idea that most who claim it just don’t have good records, but even if the historic claim is valid, it doesn’t follow the coin (or sperm) is unfair.