Clair McArthur was the mother of Donald Earl McArthur, otherwise known as The Father.
Clair became pregnant out of wedlock and gave birth to Donald in June 1964, when she was only 19 years old (meaning that she was born in 1945). It was not acceptable by her community to be with child out of wedlock. Because of this, and the fact that she was only 19 years old, and it would be difficult for her to care for him at that age, she reluctantly gave him to the church to have him be raised in the ‘Sons Of Our Father’ program. Unfortunately, some of the priests that raised him abused him sexually, which resulted in him becoming a pedophilic serial killer, as well as a serial killer of those he considered to be heretics after he turned to murdering them to try and control his pedophilic urges. 
- Clair is mentioned twice in the game. The first time is when Donald states that he was forsaken at birth. The second is when he asks Elora about the worst thing she has ever done. The player has the option of picking "I shoved six grams of coke up my ass and fucked your mother!''. Donald will get mad and respond that, although he never knew her, he knows that she died years ago.
- Because Donald is 51 years old at the time that the game takes place, and he mentions that Clair died years ago, she couldn't have lived to be any more than 68 years old. This means that Clair died relatively young by the standards of modern times.