Poor Peter! How come so many of his lady-friends have trouble-prone relatives?
Betty Brant's brother Bennett had his gambling debts, and Liz Allan's step-brother is Mark Raxton, who became the Molten Man!

from Amazing Spider-Man Annual #13 (1979)

First appearance =
Amazing Spider-Man #28 (September 1965):


And from
The Official Handbook of the Marvel Universe Update '89 No. 5 (November 1989),