The legal status of slaves was determined primarily through their maternal descent. The Colony of Virginia was the first to legally define slavery as a lifelong hereditary condition in 1662. In 1667, another Virginia law was passed that clarified that religion would play no part in someone's status as a slave. Previous to this, many slaves argued that their Christian status entitled them to freedom. As more and more slaves became Christian—forcefully or otherwise—this justification for freedom became untenable if lifetime servitude could persist. Therefore, laws established slavery as something one was born into by way of inheritance.
Whether or not a slave owner could provide basic care for their slaves was also irrelevant. There were even laws protecting a slave owner who killed a slave. The birthplace of the slave did not matter either. At first, many slaves were brought from overseas. Either they had been captured in Africa or bought from other the international slave market. Later, others were born in the colonies to these slaves. This became preferable to many slave merchants as there were fewer costs associated with the domestic slave trade.
Interestingly, tradition and law favored paternal heritage for free people. Long established English practices of inheritance dictated that children received their social station and property from their fathers. This was not the case with slaves. Lawmakers and slave owners did not want slaves making unprovable claims that their fathers were free and therefore they should be too. It was also much more common for a white man to father a child with a black woman. Rape was one of the many horrors of slavery. By ensuring that offspring would have no legal rights and was legal property, the father had no legal or moral requirement to care for the child.