DNA matches on both sides of family

[Rosezi]

Why does one of my DNA matches on Ancestry have shared matches with both my parents side? My dad and all his family are from Caithness, Scotland and my mum's side are all from Ireland and Wales and England. this is completely weird.

[Mike in Cumbria]

If you go far enough back, we're all related. You only need to go back a few generations and you have hundreds of ancestors, so there must be a shared relative somewhere along the line. Are they very distant matches?

[avm228]

I have matches like this in the 4th-6th cousin range, mostly in the US, Canada & Australia. Some siblings and cousins of my father’s ancestors will have emigrated, as will some siblings and cousins of my mother’s ancestors, and they will each have contributed to the gene pool of their new nation so that these countries now have a small proportion of people descended from both and thus related to me on both sides.

[Rosezi]

Thank you, that makes sense. I have about 370 4th cousins or closer who are all descendants of my fathers Scottish side and they all emigrated to the USA, Canada, NZ and Australia.  I think I can work out that a Scottish relative from my dad's line emigrated to Australia and married someone from my mother's Welsh side.