Young children observing their parents/adults are like single people observing young married couples. The shared way in which they observe and learn is this: it is an instinctive directional growth, to mature into that which you are inherently geared to mentally absorb everything you see about.
Kids are not destined to always remain children. It's commonly known that children notice things that their parents or other adults don't expect them to. And besides simply observing that they pick up on things that they're not often given credit for, I want to posit that the reason kids are like this is because God has geared them that way from the very start. It's in their spiritual DNA (nothing mystical is meant by that) to be influenced by and model behavior of adults. They're made this way so that they'll grow up instinctively, as opposed to growing up being a conscious decision for them to attempt to begin to do. Of course, I'm not denying that children exercise their moral agency in acting out what they imprint from adults. But ask a child why he does what he does, and good luck! They just do. It isn't conscious.
This brings me to my parallel. While the child might not be conscious of their inherent predilections, I'm older and have spent much time analyzing why I do things, think things, and how and why circumstances are and ought to be. Absent a conversation partner, in moments of solitude I have ample time to devote to introspection. I am, perhaps uniquely among most people my age, or people in general, very capable of psychologically analyzing myself on multiple deep levels. [Caveat: certainly, my conclusions are colored in part by my experience] This is just to preface what I say next: I have noticed myself observing young people in relationships, whenever possible, and I've pondered this and suppose that I'm interested in learning anything--not anything in particular, because I don't know what there is to learn--that I can, by watching how the husband and wife interact with each other, and how they talk about each other in the other's absence, for instance. Body language. Etc.
I settled on an analogy with the young child, because I recognized that it wasn't a primarily rational choice, but an instinct. And also, I have not noticed this with younger people, or people who are clearly in inappropriate or destructive relationships. That led me to hypothesize that I'm naturally geared toward "looking up to" young people who are a few years older than me (3-10), and are married, in a seemingly healthy and joyous relationship. Ah, and that they are or appear to be Christians of sound theology. As you can see, these are all things I yearn for myself--perhaps the child does not know that he yearns to be an adult, but perhaps he does. That's an interesting thought in itself, worth exploring--and so it wouldn't be unreasonable to me at all, if I were to find out that single people do "imprint" on married people. I have some sense of this already, in that unmarried women, perhaps Hollywood-stereotypically, obsess over bridal catalogues and weddings/dresses, because that's what they're drawn to; they want to be a bride. Maybe I'm just experiencing a male version of that. And more low-key, because Hollywood hasn't told me what to think (something to be grateful for, and if I find a lady who hasn't been influenced by the modern conception of what a wedding must be like, sparks may fly...is that phrase usable in a positive way?).
Keeping an eye out for a good relationship by keeping an eye on good relationships,
~ Rak Chazak