Thanks for reading. Why would you do that to yourself, though? The others just ignore us, as they should.
I've been around this thread long enough to no longer be interested in following discussions about Solas's butt.
This was something interesting, a topic (psychology) I know about, and it caught my eye simply because the tone of the debate was a bit passive-aggressive and I wondered why. However, I prefer discussions to simple chat, so this was right down my alley. Still, I don't think the others ignore you just because they do not get involved.
But how else do you propose preserving a specific bloodline if it's nearly wiped out? It's not such a different concept from Tevinter selectively breeding for magical ability. If you value the Lavellan bloodline and want it to continue, you need to procreate. And having children with someone you don't love because you perceive a larger purpose to it is what happens in both Tevinter and Orlais - Tevinter to produce more powerful mages, and Orlais to solidify political alliances. I don't feel it's weird for Dalish elves to do the same for the perpetuation of their clans.
To answer your question: by genetic variety, as it is done in our world in "normal" families. You usually keep a family bloodline alive not by breeding with your kin but with others, bringing in new genetic material. Wherever we do find incestuous relations it hardly leads to physically strong and healthy offspring in the long run.
And if you do wish to make children for the purpose of breeding you still do not have to stick with that person as a partner, you can marry somebody else after all.