You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Jews

Context:
Judaism shares some of the characteristics of a nation, an ethnicity, a religion, and a culture, making the definition of who is a Jew vary slightly depending on whether a religious or national approach to identity is used. Generally, in modern secular usage Jews include three groups: people who were born to a Jewish family regardless of whether or not they follow the religion, those who have some Jewish ancestral background or lineage (sometimes including those who do not have strictly matrilineal descent), and people without any Jewish ancestral background or lineage who have formally converted to Judaism and therefore are followers of the religion.

Question:
In modern secular usage Jews include how many groups?

three