I'll answer your questions

If Mitochondrial Eve chose a sexual partner on the grounds of what I'm going to vaguely define "cultural selection", to be distinguished from natural selection or sexual selection, could this be construed as a violation of her DNA's design/"will" to produce genetically/phenotypically robust offspring and thus be construed as a genetic Original Sin?

Fingerless gloves, gloves with fingers, or mittens?

Microscopic creatures aren't capable of sin, no matter how cutesy their names are, or how poorly conceived their reasons for choosing a partner for reproduction. Only living things with masses greater than 1kg can be sinful. I'm surprised a biologist like yourself wouldn't have known that.

For not burdening your fellow questioners with Original Sin, you will be given the First Key to the Master Chest. The Master Chest requires 5 keys to open. There are no duplicates. Once all the keys surface, you may have to negotiate with other questioners to obtain the full set, if you are not already in possession of them.

A glove without distinct fingers cannot be a glove. Fingerless gloves and mittens are both beyond saving. I need a glove that can protect, that can be stylish, but can also be useful.