This idea came to me as I was reading through a post about others giving their type impressions of me. Please bear with me, I haven't thought this through that well..
I believe it is possible that your parents, siblings, and other important people in your life can impose a significant affect on your personality through your various interactions. Of course, your parents have the greatest affect on you compared to anyone else. Assuming that you have had a decent relationship with them. For an example, my own family consists of: my mom who is an EIE, my dad who is an SLI, my brother who is an SLE, and my sister who is an SEE. I am fairly certain of these typings since I have known them my entire life and it is always much easier when you know your own type, which I am fairly certain is ILE. Having my mother constantly hammering her at me has definitely lead me to be able to keep a positive atmosphere and to respect other people's beliefs, opinions, etc. without wanting to quickly destroy their faulty reasoning. I believe this also tamed my a bit and made me not so harsh and critical of certain things. This also would make my mobilizing function happy (no pun intended), as well. She would, however, annoy me pretty thoroughly with her as I am good with that when I need to be and too much of it would lead to an argument of me trying to prove I'm not an idiot (although that's not what she meant of course). My parents divorced when I was young and although I didn't see my dad too much we still were in fairly frequent contact, so there was definitely not as much influence from him than from my mom. My dad through his , has definitely taught me to respect stability in life and would constantly remind me to relax and take it easy and don't stress over the small stuff. As I was growing up he also gave my some perspective and encouraged me to "just get it done and move on" which I am grateful for now, as I am going through the torture of required classes in college. I did not see too much of my brother as I was growing up because he was/is as mercurial as they come. Characteristic of a rather immature SLE I'd say. I would mostly regard what he would tell me as nonsense any way since I felt his to be a little abrasive. My sister is also on the immature side, but we would at least have a fun time together. Mostly we would do superficial activities together like watch movies, etc. We would really bond when we were both frustrated with my mom and she would help give me some perspective on in a subtle kind of way that was easy to understand and not too irritating as would be a dominant type. Aside from my family, the most profound affect on my type has come from my current duality relationship with an SEI. Through this relationship I feel as though I have started to see myself from a whole different perspective and I have changed quite a bit from how I used to be. It would be too much to type out right now, but let it be sufficient to say that it has been quite the experience. On a side note, I would like to say I have had a lot of alone time through out my life and probably don't seem like the "average" or stereotypical ILE, but I cannot see any other type for myself. I am still open to feedback, however.
Well this actually turned into a familial analysis more than an actual theory, but I think it is important nonetheless. I believe this can help shed more light on your type being affected by others' types. I'm sure I have had an affect back at those who have had an affect on me, but due to my PoLR being I'm not very adept at understanding relationships (which I am more than happy to acknowledge and admit(to those who would understand at least)). I suppose what I am getting at here is not only can you analyze what kind of relationships you have with others, but you can reflect on these relationships' affects on you and others. Which can bring you some enlightening insights into your current cognition and behaviors.
I would love to hear others' personal experiences with important figures in their lives and possible affects on their type! Also be wary that due to conditioning this may cause you to mistype yourselves and essentially be the product of your parents, etc. vicariously living through you or something of the sort. Just more food for thought