Absolutely, but to frame that sentiment in the analogy with sex that the GP made would be something like "we have a natural urge to have sex, therefore we must

Absolutely, but to frame that sentiment in the analogy with sex that the GP made would be something like "we have a natural urge to have sex, therefore we must protect sex toys". (That may or may not be a valid argument with respect to sex toys, but my point is it's a different one than presented above). Put differently, "natural predisposition to protecting self and family => self defense OK" is not the same proposition as "natural predisposition to protecting self and family => guns OK". There's an extra step in the latter, "self defense OK => guns OK" (which I was not making an explicit evaluation on). The analogy in the GP is a false equivalence.