Bengali Brahmos are those who adhere to Brahmoism, the philosophy of Brahmo Samaj which was founded by Raja Rammohan Roy.
A recent publication describes the disproportionate influence of Brahmos on India's development post-19th Century as unparalleled in recent times.
[1] One aspect of Brahmoism is recognition that not only explicit faith and worship makes for a Brahmo, but also genealogy, which is implicit.
This often causes tension within the Samaj, for example, when an offspring of a Brahmo follows atheism or another religious belief without renouncing Brahmoism formally.
There are differing views between the Theist and Deist streams of Brahmoism on the retention of such people within the fold.