ADC, Mid and Top laners: Whose fault is it when you lose lane or feed?

Everyone but Mine.

wheres the 'self' poll?

Yours.

No one's fault. Only the person who was doing faulty. Sure there can be some exceptions where the jungler miss timed a gank or the supp did't land a hook but when everyone is playing well it might just be the enemy is playing better.

It could be supports fault for their lane losing, sometimes you just cannot carry a really bad support (I am one and know that I am usually the reason I lose bot if I support).

Other lanes, it is generally their fault.

Whoever is too blame. I'll blame myself for losing, because in reality it is a 1v1 lane (mid), but at the same time, it can be frustrating when the enemy champion is pushed all the way to your turret and your jungler ignores it. It's your fault for losing lane, but it's also on your jungler for not taking an easy gank. That's why it's a team game after all

Riot's fault. Its matchmaker placed your teammates with lane opponents too strong for them.

Unless said person literally walked into the other team and purposefully fed them, I generally regard it as my fault or just an unfortunate mistake

We all know its !!!