Weak nails?

I have a personal theory.
Girls who bite their fingernails tend to have short (base part, not nail tip) and weak fingernails
Girls who never bite them tend to have long and strong fingernails.
My sister who is 10 years older than me used to bite her nails until she was about 20 (now 31) and her nails are kind of weak and short at the base. I stopped biting mine when i was less than 10 years old.
She is jealous of my fingernails because they're always long (both base and tips) and never really chipped, are regularly French Manicured by my friend who works at a beauty salon, she does a really nice job: http://img600.imageshack.us/img600/2760/765q.jpg

I think you could be right actually. My sister doesn't bite her nails and her nails are really strong and grow quickly. And we both eat pretty much the same foods, so I don't think its my diet that is affecting my nails.
Your nails look great btw!