. >> reporter: for four generations, michael guinan's family has made a living from this modest dairy and beef farm in the irish midlands. >> this is a family farm. and my son is here with me now full time. and it's becoming increasingly difficult to get a living for two families on the farm. >> reporter: difficult thanks to uncertainty surrounding the future trading relationship between the republic of ireland and the united kingdom. >> nobody saw brexit coming. we talked about it. we sat back and said, "nah, it can't happen." but it has happened. >> reporter: the united kingdom- - england, scotland, wales, and northern ireland-- is the republic of ireland's biggest trading partner. around $1.3-billion worth of goods and services criss-cross the border every week. but those commercial ties could be frayed by brexit. this is the border between northern ireland and the republic of ireland. right now there are no border controls on goods and services moving between the two countries, because they're both members of the european union. but when britain pulls out of the e.u., it could tri