All the strong "don't do it" opinions from people who aren't into genealogy....
And yes, I have listened to the podcast, well, some of it. It's not all about finding your dad is not your dad or you have a half-sibling. Personally, I didn't like it much as a series, quite preachy I thought. I have lots of experience with DNA testing for genealogy, although not quite at the spreadsheet level. I have done basic Ancestry tests on both me and DH, and a Y-DNA test on my dad.
The NPE - not parent expected - is nothing like 5% or 10%, it's more like 1% or 2%. https://isogg.org/wiki/Non-paternity_event Although you could argue that DNA tests are throwing up a higher percentage than in the general population as people who are unsure about their parentage are more likely to test than others.
My test showed very little of interest. My paternal line all came from the same small rural area, worked as agricultural labourers, and did so for centuries. I had very few matches - probably because everyone knows that their ancestors have deep roots. My maternal side has very few matches, but again, no surprises.
DH's test was fine on his mother's side but had no matches with his surname on the paternal line which was the first indication something was off. His g grandmother was 7 months pregnant when she married in January 1905. His grandfather was born on 30 March of the same year. The person she married was not the father of her baby. This may be a NPE, may not. We do not know whether her husband knew he was not the father of the baby, or whether he was well aware and didn't care.
The DNA matches, several of whom had the same surname, have given the bones of the story. Martha, who got married at 7 months pregnant, was living in the NE of England in a port town. The DNA matches indicate that the father of her baby was a man whose surname is strongly associated with the NE of Scotland and fishing communities around the Moray Firth. Unfortunately these families with that surname all had multiple sons who went to sea so we haven't been able to narrow it further.