Not true. There are relationships (for example between mother and child) that are not based on reciprocation. Nothing in the definition of the word "relationship" implies expectations or getting something in return. It's a synthetic proposition, not an analytic (tautological) one.
Is the mother child relationship really not based on reciprocation? The child doesn't enter the relationship willingly which makes it more interesting, but most people that I talk to who want kids do have an expectation of why they want kids. I specifically don't want kids, so this is always of interest to me.
BTW, not trying to debate necessarily as I don't have a strong feeling on either side. I just found this article and your comment to be interesting.
Like giving money to charity, there is no personal gain from giving to organisation that will provide some unknown form of aid to children across the world. Yet it is worth it for some people to make the donation. As selfless as giving to charity is, having a child is magnitudes more selfless (unless you fully expect your child to care for you later in life).
Cost, time, stress, etc. At the benefit of seeing a part of you live on and be happy.
BTW, not trying to debate necessarily as I don't have a strong feeling on either side. I just found this article and your comment to be interesting.