Ideas, that in these other people's lives, are maintained as reality. You will tend to adopt their beliefs and facts as your own. This can be scary, but there is no danger to our sense of individuality from this merging. When we talk and exchange thoughts with others it can become unclear whose thoughts are whose, especially when they are trying to convince us of something. Thoughts aren't neutral.
Thoughts emerging from strongly held beliefs have the appearance of reality.
We might not believe the ideas others describe, but as we perceive them, we become the ideas they describe. I've found most people I talk to are somewhat confused as to what they personally believe. Their belief systems are a conglomeration of beliefs they have gained from their parents, their education, the media, and from whatever religions to which they may have been exposed. Many of their beliefs contradict each other which leaves them confused. If this is one of your problems, the way out of this dilemma is to begin writing your beliefs down on paper or, better still, if you have access to a computer or word processor use it to record your beliefs.