Jo’s devastating backstory has begun to unravel (Picture: BBC)Line Of Duty series 6 has some serious complicated relationships on the go at the moment, as the show runs towards its finale next week.
One of the biggest bombshells of the season was the reveal that DCI Joanne Davidson has a blood relative connection to the OCG (Organised Crime Group).
It’s clearly left her vulnerable to manipulation – even ending up in a shoot out at the end of episode five.
But what exactly is she hiding? Steve Arnott and Chloe Bishop knows it’s something to do with homozygosity – but what even is it?
Here’s what you need to know.
What is homozygosity?
A note suggested Tommy was Jo’s father and cousin (Picture: BBC)Homozygosity is the possession of two identical alleles of a particular gene or genetic sequence.
While all humans are made up of the same genetics, there are certain variations which are only present in family members.
Each gene is made up of two parts (alleles) – one from the mother and one from the father.
There can be either dominant or recessive traits, and effect things such as hair colour, eye colour, or genetic diseases.
What does this mean for Jo Davidson?
Tommy Hunter was a key member of the OCG in series one (Picture: BBC)When Joanne’s connection to Tommy Hunter was revealed, it was noted by Steve that her homozygosity was ‘unusually high’ – which suggested a specifically tight genetic make-up with him.
While she was noted at the time to be simply a ‘blood relative’, unusually high homozygosity suggests there’s something more at play.
Fans have since spotted on an investigation board a note that reveals that Joanne was the result of an inbred relationship.
More: Line of Duty
The note reads: ‘Jo Davidson’s DNA has been identified at Farida Jatri’s house.
‘A match has been made to Tommy Hunter stating she is both his niece and daughter.’
Line Of Duty airs Sundays at 9pm on BBC One.
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