That is exactly how I was taught human genetics about forty years ago.
Have there been developments since then that describe a process whereby some information gets exchanged between the members of a pair of chromosomes before meiosis takes place? I think the process is perhaps not as simple as some of us were taught and that the math you describe, although correct for the simpler model we were taught, is not, in fact, what actually happens.
Perhaps there is a recently trained geneticist reading this thread who can clarify this.
There’s a little bit, yeah. There’s nothing significant enough to alter the basic model to the extent as has been claimed somewhere around FR (another topic, perhaps a year ago), by some nimrod who claimed that the result was that *exactly* one quarter of our genes came from *each* grandparent. The basic math is good enough to get the basic understanding of what’s going on. Or course, given that the human genome data currently available indicates that everyone’s got almost exactly the same DNA (much of it “junk DNA”), none of this matters, eh? ;’)