I too wonder about anyone who is studying their holy book in public. But that is a case by case basis. Being a Wednesday in the middle of summer, Dad could have have taken the kids out to the park to get them out of the house and decided to read some torah on a nice sunny day. Doing it on the subway? No. Stop.

Also dad's dad could have been a tall blonde german man who met and married a very light haired and light eyed jewish girl. And that bred very Aryan babies.

You don't meet a lot of converts and they are usually the spouse of a Jewish person who converted to get married. And if that guy converted to get married, he's not studying the torah at the park. I mean to say that they take it seriously, just not that seriously.