I'm a little wary about genetic engineering, and especially the ethics involved. Just because you can do something doesn't mean you should. Yes, we can learn a lot through research into stem cells etc and genetic modification, and I agree with that up to a point. I've got no problem with therapeutic research, where the aim is to find the genetic causes of diseases and, if possible to eradicate them, but if you have to end one life to save another, is it worth it?
A fertilised egg is a potential life, but it only begins to fulfil that potential when it's implanted, which can be a bit hit and miss, so I have no problem with IVF from that point of view. It's just a slight extrapolation from what happens naturally anyway. I think if parents choose to have a child using IVF to become a donor for a sick child, that I do have a problem with. What right do they have to decide that that baby will give up its organs, bone marrow or whatever to save its sibling. Will that child ever be anything more than a donor to them?
With inherited diseases, things are a little more complicated, but again, who are we to decide whether a person is going to have a fulfilling life and be a contributing member of society? Ask Stephen Hawking how he feels about his life and whether or not he's made any contribution. The other thing to consider is that we are learning more and more about the causes of inherited diseases and are getting closer to finding cures for some. Who's to say that we won't find a cure for muscular dystrophy or cystic fibrosis during the person's lifespan? The logical extrapolation from the argument against allowing foetuses with genetic disorders to grow into children is to prevent carriers of genetic disorders breeding and eradicate the diseases that way. How ethical is that? It would be easier to do and more cost-effective than research into cures for the diseases, but I don't hear anyone advocating that as an option.
On the subject of abortion, I must say that I'm against it unless there's a very good medical reason, such as the prenancy endangering the mother's life. I know I'll put a lot of people's backs up by saying this, but if a healthy woman gets pregnant and doesn't want the child, there are plenty of couples (and singles) out there who would love to raise the child for her. I know it's not as simple and straightforward as having a baby and handing it over, and that the whole process of pregancy and childbirth can be very traumatic to a woman's body and emotions, but I think that child has a right to life. I fully support contraceptive use, up to and including drugs and devices which prevent implantation, but once that's happened, I think the foetus should have rights and legal status as a potential human being.