Do you mean between Yahiko (who we've never seen use any skills) instead of Yamato?

If you do mean Yamato then maybe you should reread the chapters where Oro frst encounters Yamato and remarks on how he thought all the subjects of "that experiment " had died. Oro cloned (or spliced) the genetics of the 1st into people somehow but apparently the process or results weren't to his liking so he trashed the project. Yamato survived, grew up and demonstrated similar abilities to the 1st.