I can't believe I'm asking a genetics 101 question, but I guess everything gets rusty after a while. 'Someone close to me' is convinced that she has no genes from her paternal grandfather. Since he is the only Italian in her ancestry, she believes that, genetically, she has no Italian heritage. Her logic is thus: - she has two X chromosomes - that means she got an X from her father - her father has an X and Y, thus he must have gotten the X from his mother, which means he must have gotten his Y from his father. - since she has no Y, she did not get her paternal grandfather's genes. Which means she has no traits (eye colour, nose shape, risk factors, and racial heritage, etc.) inherited from her grandfather. SCTM is no fool in biology, and is actually better educated than I about it, but I think there's a gap in her picture of chromosomes. She knows the chromosomes divide and recombine during cell division, but it seems she believes they all do so together, meaning there's no way he genes could contain any from her paternal grandfather. I am trying to convince here that she is only describing the single sex chromosome, and that there are 22 other chromosomes, any number of which, from 0 to 22, she might have inherited from her paternal grandfather. I'm not 100% sure I'm right, or exactly where/how the genes/chromosomes get mixed. Can someone point me to a concise description or diagram that shows how chromosomes get mixed and recombined from one generation to the next?