I'm not a biology student. So, I humbly request you to limit yourself to the basics, please do not indulge in infighting. If you ignore the request, you would be investing your efforts at the wrong place and perhaps it would be considered a pretentious show of knowledge. There are 23 pairs of chromosomes in a human body cell, 46 chromosomes in total. All cells have identical genes but themselves are different excluding the 23rd pair sex chromosome which has different set of genes. Female sex chromosome is called 'Y' and male 'X'. If the combination is: XX = female YY = male XY = YX = ? 1: What would be the result of 'YX' combination? 2: How many genes are there per human cell? I read somewhere it's close to 35,000. Is this number for 23 pairs or just 23 chromosomes? 3: Are the genes of all humans the same? I think they aren't - if they were, the humans would look alike. It's a silly question, probably. Perhaps, my question is an inquiry on something else. If humans started from the same, then why is the pool full of so many different genes?