One of the interesting things about football that singles it out as a field, is that the scouting network is now simply so strong that, if you're a child who is extremely good at football, and who plays at all for any kind of little local club, you will come to the attention of an academy scout without having to do any more than that and of course no specialist equipment, training or parental attention involved. Everyone has encountered football, pretty much the world over. Most boys, and many girls, will play it casually at lunchtimes at primary school, so you will discover if you are good unlike, say, discovering a talent for a particular instrument, when you would have to have had access to that instrument in the first place.
I agree with @Thepeopleversuswork -- people are confusing 'gifted' with 'extremely good' on the thread, though. I am not gifted, but I am clever, and got a scholarship to Oxford, despite my parents struggling with literacy and attending a school in which few students went on to any form of post-school education, so I had no support and filled out the forms etc myself and sent them off (back in the paper days!)
My parents are frequently puzzled by me, and my mother always says 'Where did you get it from?' The fact is that it's impossible to gauge genetic inheritance of IQ when no one before you in your family had any education or opportunity -- my family on both sides were very poor, and tracing as far back as I've been able, they were illiterate farm labourers. Who knows how clever they were, or what they might have achieved, in other circumstances?