No, a man cannot only have Y sperm. Men have two types of sperm cells: X sperm and Y sperm. The X sperm carries the X chromosome, while the Y sperm carries the Y chromosome. This is because a man's sex chromosomes are XY, while a woman's are XX. When a man's sperm fertilizes an egg, the resulting offspring's sex is determined by which chromosome the sperm carries. An X chromosome will result in a female offspring (XX), while a Y chromosome will result in a male offspring (XY).
While some men might have a slightly higher or lower percentage of X or Y sperm, it is impossible for a man to produce only one type of sperm. This is because every sperm cell is created through meiosis, a process where the sex chromosomes are separated and packaged into individual sperm cells. This means that each sperm cell has a 50% chance of carrying an X chromosome and a 50% chance of carrying a Y chromosome.
