I am learning about meiosis in biology. I've learnt that the crossing-over in metaphase I only exchanges small portions of DNA at the tips of the chromosomes. Doesn't this mean that:
- After meiosis I, there will be two cells that will be almost opposites (for each chromosome, if one cell has the mother's chromosome, then the other will have the father's chromosome), except for the parts where crossing-over happened
- After meiosis II, each cell produced in meiosis I will produce two similar cells (the only differences will be where crossing over happened in one but not both of the chromatids)
This means that there would be a rare chance of two of the sperm cells produced by a single meiosis fertilizing two eggs, in which case we could have:
- Almost-identical twins
- Very different twins, which would have less than the normal 50% of DNA in common
Am I right about this?
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