So, old story my dad told me. Not 100% on the accuracy, but basically if you want a male, wait and let the male spermies accumulate before attempting. While there are less of them, they typically swim faster and waiting for a bit gives a chance for them to accumulate to sway the odds. If you want a female, just keep going at it. Body produces more female sperm so chances are higher for this outcome. Evolution wise I guess it would make sense as you need more hosts than seed slingers...