Isn't Sean Astin Patty Duke's and some guy other than John Astin's boy? (Sean just took on the Astin name)
As I remember,
Patty was dating Ricky Arnez Jr. at the time too...so when she got pregnant, everyone thought the baby was his, but then she married Astin...but for years, everyone STILL thought Sean was Ricky's.
But Sean grew up thinking Astin was his Dad.
THEN it came out that Sean's father is a third party that Patty was dating.
Now if that ain't confused, I don't know what is.