Freshly Baked Science
Who's The Daddy?
31st July 2018
In light of the release of Mamma Mia: Here We Go Again, we've decided to take a look into how Sophie could find out which one of Sam, Bill and Harry is her real father, to settle the debate once and for all. Although she is now happy with having three dads, the curious among us still want to know for sure which of Donna's love interests managed to sow their seed.
Thanks to science, it is actually possible to find out who somebody's father is by DNA testing. When used for this purpose it's called 'paternity testing'. It is also possible to do maternity testing which is to find out who somebody's mother is, but this is very rarely done as the baby growing inside the mothers womb is pretty strong proof.
The test is usually done by taking a swab of the inside of the cheek (known as a buccal swab). The cheek is used because the cells are very easily shed from the lining of the mouth and these cells contain DNA which is needed for the testing. These swabs are taken from both the child and the possible father.
The DNA from the cheek cells is released by breaking open the cells and separating the DNA from everything else inside the cell. A technique is then used which is very much like a DNA photocopier, which will make many copies of 21 specific areas of the DNA so that there is plenty to work with.
When the DNA has been collected and multiplied, it can be profiled. This where the number of repeats of letters in the DNA sequence at 21 specific areas is recorded. Each person will have two numbers in each area (one from their mother and one from their father). So for example, if at one area a mother has 2 repeats and 4 repeats and the father has 2 repeats and 7 repeats, the child could have 2&2, 2&7, 4&2 or 4&7.
For a paternity test to be positive, the man and the child must have a common number at every one of the 21 areas. Because everyone's DNA is unique, it is very unlikely that you'll have a match in every area against someone who isn't your mother or father.
So for Sophie to find out whether Sam, Bill or Harry is her real dad she would have to give her own cheek swab to a scientist, along with a cheek swab from her 3 'dads'. Whoever has the matching numbers with Sophie, would be her dad!