Which character is Polly Gray's biological son?

Polly Gray's biological son is Michael Gray.

Polly is separated from Michael and his sister Anna when they are young. After years apart, Michael is located and brought back into Polly's life at age 17, becoming part of the Shelby family and the Peaky Blinders. He is portrayed by Finn Cole.

Michael initially works on the legitimate, accounting side of Shelby Company Limited, contrasting with Tommy Shelby's criminal operations. His return also changes the family's balance: Polly gains the son she lost, while Michael must adapt to relatives and a criminal organization he barely knows.

A common mix-up is confusing Michael's family connection with the Shelby siblings' direct parentage. Michael is Polly's son and therefore the Shelby siblings' cousin, not Polly's nephew. Later, grief over Polly's murder turns Michael against Tommy, leading to their final confrontation.