No one is Christian by birth even if ones parent or parents were followers of Jesus.
If his parent or parents proclaimed Jesus Christ as their Savior and Redeemer, they did that by their personal choice, with the prompting of the Holy Spirit.
Becoming followers of Christ is not genetic nor carried in ones DNA but by personal decisions to turn ones life around and proclaim salvation by one way, the only way, through the blood shed on the Cross by Gods substitutionary lamb sacrificed for His creation.
Important point that a non-Christian would not comprehend, thanks!