There are known genetic factors for crying easily.[1] My oldest son and I cry easily; my wife and youngest son don't. By "crying" here I mean tearing up in response to both positive and negative emotions, including emotions expressed by others. My oldest son and I are about normal when it comes to outright bawling or crying in response to physical injury.

Some public individuals cry easily: definitely John Boehner and possibly Elon Musk.

[1] http://blog.23andme.com/health-traits/too-many-teardrops/