Confused about Haplogroup results

So don't laugh but I am having a little problem sorting out the results of my father's previous DNA results done with the Genographic Project and of my sons's done at 23 and me in the last month.

So here's the conflict -

Father done at Genographic = I 1b2a (about 2 years ago)

Son done at 23&me = I CTS616

Me = confused as **** !

Any help ?