Conversation so far:
Who was Fischer's father?
Sources implying that Paul Nemenyi, a Hungarian-Jewish mathematician and physicist and an expert in fluid and applied mechanics, was Fischer's biological father.
Did Paul Nemenyl have any great achievements?
CANNOTANSWER.
What roles, besides father, does Paul play as Fischers father?
Nemenyi made monthly child support payments to Regina and paid for Bobby's schooling until his own death in 1952.
Who is Bobby's mother?
Regina.
Did Bobby  Fischer have any notable achievements?
CANNOTANSWER.
Is there any other interesting information about Paul Nemenyi?
Nemenyi had lodged complaints with social workers, saying he was concerned about the way that Regina was raising Bobby.

Question: What concerns did he have about Regina raising Bobby?
Self-contained rewrite: What concerns did Nemenyi have about Regina raising Bobby?