Just remember, Leonard, where
your BIOLOGICAL family has failed you...
The Big Bang Theory Season 3, Episode 11
Well, there is
a deep-seated BIOLOGICAL drive
The Big Bang Theory Season 12, Episode 12
That's a BIOLOGICAL impossibility,
and you didn't have to come.
The Big Bang Theory Season 1, Episode 1
I realize you're currently at the mercy
of your BIOLOGICAL urges...
The Big Bang Theory Season 3, Episode 1
has got my BIOLOGICAL clock
ticking like crazy.
The Big Bang Theory Season 11, Episode 17