This post is more personal than anything else. I'll admit, I have not consulted the Catechism or USCCB (U.S. Conference of Catholic Bishops) about this, so if you're looking for something more official, this isn't it. However, as my fiance and I both carry an interesting set of genetics, it's been suggested by friends and family that we undergo genetic counseling. I've come to the conclusion that such can be licit for Catholics, as long as it's for knowledge only.
I would like to undergo it, simply to understand the health history of our families better. If we are carrying risks for certain disorders, knowing how likely we are to pass certain traits can help me better prepare if we did have a child with any of those disorders. For me, it would be like learning that your child has Down's Syndrome (in the womb). It would help me better prepare for the future and learn what resources exist for children with different disorders. This would help me understand whether I'd likely have to stay home (as opposed to taking maternity leave and returning to work), hire medical attendants, or figure out special education, as well as how early a child I have can be tested for certain things.
However, there are certain recommendations I'd never be able to take as a Catholic. One, I can't decide to simply not have children if I'm married. While I am allowed to use fertility awareness as a method of birth control, I still have to enter into marriage open to having a biological child (so, no, I can't get sterilized and neither can my husband). If I happen to not have children by mere circumstance, I'm not obligated to put in extra effort (whether through pills or adoption). I simply have to be open-regardless of what my genetics tell me.
I also cannot terminate a pregnancy. As a Catholic, that's self-explanatory. While I do have options if my life and the baby's life were in danger (and the doctors can only save me), I can't directly kill a child within my womb. This isn't simply religious teaching for me, it's an ethical one. While some may say it's more merciful or that you can't expect parents to change their lives so drastically, it's not an acceptable decision for me. Every life is worth living and, in an age where people with disabilities can live longer, happier, productive lives than ever before, there really is no excuse for certain disorders. Also, a child or adult can become disabled later in life. The difference here is that I'd have time to prepare and make arrangements.
In addition, I can't go through extraordinary means to have a kid. Assisted reproductive technologies (different from treatments that simply stimulate ovaries or increase sperm production) are also not allowed for any reason. Some genetic counselors suggest in vitro fertilization so that only healthy embryos would be selected for implantation. As in vitro is forbidden and it would mean that unhealthy embryos would be destroyed, I can't licitly choose that as an option.
It sounds like there are a lot of restraints for me to plan a family, even with genetic counseling. However, choosing to have a child is a sign of hope for the future. I would have my child regardless of whether or not he or she had disabilities. I choose to love any child that comes into my house, biologically or not, simply because I believe that there is a future for anyone who lives on this planet. At the same time, with this love, I'd choose to be prepared so that I could be the best parent I could be. So, yes, I do think genetic counseling can be licit for Catholic couples, so long as they abide by moral responsibilities in terms of family planning.