All sinned because death passed through to all. Death passed through to all mankind, on which all sinned. Death is the channel of sin. Death came through to all mankind. All men are mortal.
Sin is a by-product of mortality.
The transmission of death by generation presents no problems. It is simply the lack of sufficient life, a deficiency in vitality, of all that flows from the life abundant. We are severed from the Source of life. Men are denied access to the tree of life. They are wanting of the glory of God.