In Jainism, being a Jain is mainly about faith, vows, and practice, not just blood lineage. If a Jain boy marries a Hindu girl, their child is not automatically a “Jain by birth.” The key factors are:

• How the child is raised: If the child is brought up in the Jain dharma, learns Jain principles, and follows Jain practices, they can become Jain.
• Formal commitment: If the child chooses Jain vows and is initiated into Jain practice (or consciously follows Jain path on their own), they are considered Jain.
• Guidance from the Jain community: Acceptance and recognition can vary by community and local monks or pujaris, but the underlying principle remains that Jain identity comes from practice and affiliation with Jain vows, not merely ancestry.

In short: a child can be a real Jain if they are raised in Jainism and choose to live by Jain vows; it is not automatically determined by the parents’ religions.