[To be fair, most people asked. Just... not everyone waited for an answer. (Not that Atsushi minds, but it's the principle of the thing.)]

W-Well... If you do ever see a giant white tiger, definitely don't get close.

[He wasn't wrong to say that as he did. He thinks him and the tiger are okay, now, but he definitely can't count on the tiger being okay with anyone else.]

I was born with it. At least, that's what I presume. I've been the tiger for longer than I can remember.

[Were he a real detective, he might have concluded that his limited control over his ability hinted at it being something passed down to him by someone else, much like Kyouka got her ability from her mother (and Tsujimura got hers the same way). But all Atsushi knows about his parents is that they (supposedly) abused him, and left him to die. There's no connection there.]