Stevie J Will Take DNA Test for Joseline Hernandez's Baby

Stevie J's down to get pricked for Joseline Hernandez's paternity test request but it could come back to burn her where child custody is concerned.

Stevie J just filed docs agreeing to take a DNA test to find out if he's the father of Joseline's unborn child and if he is ... Stevie's asking the court to award him primary physical custody because he thinks she's an unfit mother. In the docs, he claims Joseline may have abused drugs during the pregnancy.

He also says she has anger issues as evidenced by her acts of violence against him in the past. He claims she'll "engage in acts of parental alienation" once the kid's born and keep him away from the child.

If he's granted custody, Stevie J is also asking for child support.

TMZ broke the story ... Joseline sued earlier this month to get Stevie J to take a paternity test. She also asked for child support.