Yes, they are brother & sister.
No.
Seth MacFarlane was born on October 26, 1973
{WHERE} does Seth MacFarlane work? as of July 1, 2011: California
Seth MacFarlane
Seth MacFarlane, creator of "Family Guy," has a Scottish, Irish, Dutch, and English ancestry.
The duration of Seth MacFarlane's Cavalcade of Cartoon Comedy is 120.0 seconds.
Seth Woodbury MacFarlane
Seth Rogen is straight. He is also married to Lauren Miller since 2011.
Seth MacFarlane was born on October 26, 1973
No , Seth MacFarlane is an American who was born in Kent , Connecticut .
No, even though the do look a lot alike, they are not related.
{WHERE} does Seth MacFarlane work? as of July 1, 2011: California
who inspired Seth Macfarlane to become an artist
Seth MacFarlane, Ann (Sager) Perry and Ronald Milton MacFarlane are from Scotch, Welsh, and English ancestry.
Seth MacFarlane
Seth Gamble's birth name is Seth Craig Abbe.
Considering Todd's last name is McFarlane & Seth's is MacFarlane, and Todd is not married to Seth's sister & Seth is not married to Todd's sister (if he has one), it would be rather hard for two people with different last names to be related.
Seth MacFarlane, creator of "Family Guy," has a Scottish, Irish, Dutch, and English ancestry.