Hi. I have an older brother who is 3 years older  than me.

I do NOT know his phone number and I have never felt I need it. (even not a friend on FB).

However, I still believe that we get along well. We chat a lot when we meet, I love his niece and sister in law.

I think it could  happen if they were in different age. because of that they may have little contact in their life to each other. different friends different entertainments and... but not like what you say...