I’ve looked through the different works and various forms of elves and what their half-breed children are like.
Half Breeds in some stories look like their human parent, almost completely and I’ll explain why below… In other stories, they are mixed, though in most, they have slightly pointed ears, but otherwise look like humans.
So far, there is one consistency; elven genes are recessive when combined with those of humans. Given what we typically see of elves, I can understand that theory. Elves tend to have light skin, light eyes (Blue, green, hazel), and light hair, all of which are recessive traits in humans.
However, one point of contention that I would make would be the ears. Generally, the most pronounced features of a person would show up on their offspring, and those features tend to be more dominant. So with that in mind, I do believe that the stories that say that half-elf children would still retain SOME of their parents’ features.
In a story I’ve been working on for some time, an elven child can pass for a human as long as they keep their hair long enough to cover the more rounded points on their ears. Other prominent elven features aren’t apparent in the offspring. They have some extra-sensory perception which they receive from their elven parent, but they are nowhere near as powerful nor as easy to control. In most cases, these abilities would manifest as dreams or ‘feelings’ and nothing more.
Their hearing can be trained to be as powerful as their elven parent, but it would take much effort to train their senses and they would need to focus much more than their elven parents to detect faint noises.
Half-breeds would be less susceptible to both human and elven disease, having immunities on both sides, however diseases that affect both would have a stronger impact on a half-elf child.
So do you agree or disagree? I’m not a biology major so I could be way off, but this is my interpretation of inter-species mating. Let me know!
James Harringtons Creative Work 
What you say about recessive traits has sense. In my project, half-elves have only a few appearances, most of them passing, so I haven’t delved into it much myself. What I’ve been thinking about more is tied to their lifespan (and that is about both full-blood elves and half-elves) and how should that be approached to avoid demographical issues (either uncontrolled population expansion or population collapse).
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