Now, I've lived my whole life dealing
with the fact that my TWIN brother is...
The Big Bang Theory Season 1, Episode 15
Penny, this is Sheldon's TWIN sister.
Missy, this is our neighbor Penny.
The Big Bang Theory Season 1, Episode 15
"Made up my mind to date both of them
by pretending to be TWIN brothers."
The Big Bang Theory Season 9, Episode 14
I have a TWIN sister
whose assaults began in utero.
The Big Bang Theory Season 3, Episode 17
I grew up with an older brother
and a very contentious TWIN sister.
The Big Bang Theory Season 3, Episode 2