I'd think cycling lots from a young age would help but since you're presumably not in possession of a time machine then squatting with good form and intensity will probably help plus a good diet.
I cycled a lot from 16 nothing major but always did it and played rugby, my legs have never been skinny, even when I was ten I remember having large legs.
With some work, I could be pretty big, , need to strip down the fat to see whats what.
This was me in March, I dont know if they look big because of the fat but I was tensing.
This was me in May
Some size their, but like I said, not sure how much fat makes quads look bigger but surly I have a good base? I know they tend to split when you get low body fat but looking at the pics of the track cyclists, looks like they have bit more fat on them than body builders.
Especially my left leg it just sticks out like crazy for someone that has dont little squat routine or even leg routine, only been at the gym since March, I use to go to a gym 3 years ago.
Any info/good or bad would be appropriated.