My DS was also the same. Fine with DH and Grandpa, but any other males would have him clinging to us and crying but at the same time wanted to know where they were at all times. The worse one was his uncle because he lives in ADL and we only see him twice a year. By Sept this year he was much better would shake hands and be in the same room as him without clinging to us. He was 21mths at the time. I think over time he adjusted to seeing men and was able to communicate by saying "man" everytime he saw a man walking a dog. I think it is something that takes time and patience.