These are the traditional genealogies of rADh.I families descended from vedagarbha of sAvarNa gotra. All gaGgopAdhyAYa are of this gotra. No attempt has been made to make this page more comprehensible: it is mainly intended as people looking for their origins, and I am sure they will treat this only as material to start them off towards more serious investigation.
One set of Y-STR results are available from a Gangopadhyaya family: DYS 393:14 390:25 19/394:15 391:10 385a:14 385b:18 426:11 388:12 439:12 389I:13 392:14 389II:30, and SNP testing showed them to be haplogroup O2a1(xO2a1a) (M175+ M88- M95+; new nomenclature, used to be O2a(xO2a1) before): which is quite common among Indian tribals, especially in East India, and whose spread correlates with the spread of Austrasiatic Mundari languages from Laos to India (see here for genetic evidence for the late Neolithic spread starting 5.7(3) Kya in Laos and ending 4.3(2) Kya in East India). In fact, two samples (KH23 and KH32 there) out of 37 reported from the South Munda speaking Kharia population of the Raigarha district of Chhattisgarh State in a recent paper is 1/7 distance away from this, but slightly more distant STR patterns are seen among many of the Munda groups. This haplogroup does not match the Y-STR found for me (I belong to the same gotra): DYS 393:13 390:25 19/394:16 391:11 385a:11 385b:14 426:12 388:12 439:10 389I:14 392:11 389II:32, and SNP testing showed me to be an R1a1a(x1a/b/c), which is also prevalent among the upper castes and correlates better with the spread of Indo-european influence. Another Bhattacharya of the same gotra, (Arghya Bhattacharya, descendent of Umanath Bhattacharyya who lived c.1810–c.1900) has 393:13 390:25 19:16 391:11 385a:11 385b:14 439:10 389I:14 392:11 389II:32 458:18 437:14 448:20 H4:13 456:15 438:11 635:23, which is not too distant (2/16 corresponding to 8–111 generations at 95% confidence with a mode about 30; probably less because 458 is a rather fast-changing allele) from mine. Another person of the same gotra (RP Chakravorty) has 393:13 390:25 19:15 391:10 385a:11 385b:13 439:10 389I:13 392:11 389II:31 458:17 437:14 448:20 H4:12 456:14 438:11 635:24. A Chattopadhyay and a Bhattacharya of Shandilya gotra were also tested R1a1a (by 2010 nomenclature; equivalent to previous R1a1), though further (typically 10–122 generations with a mode around 50) on the STR scale, and some others (see those pages) were found to be R2.
It would not have been possible for me to collect this information except for the very useful book called brAhmaNa-itihAsa by shrIharilAla caTTopAdhyAYa. I have no idea how he collected all this material, and what criterion he used to select from among the available genealogies of bengali brahmins. The book has sometimes been difficult to decipher, and interested readers should look at the original to verify my interpretation.
And finally, remember, tradition is not history. Similar caveats apply to the historicity of these genealogies as apply to my own.
See my genealogy to see an alternate version (has Rajyadhar's descendants except it has Hemagarbha instead of Rajyadhara, inserts Komalanga and Shobhana after Ratnagarbha, replaces Visho by Vishoka, omits Heramba, calls Mangala as Mangali, has Sasthivara after him instead of Brahmacari, calls Roshakar as Roshakar Brahmacari, has a Rashmikar, brother of Roshakar, and does not have giridhar among the sons of Roshakar; Note that Shobhana exists in the standard list below at the right period but as a cousin, not in the direct line of descent) of the early part of this list, and kumkum's genealogy (not available on the web: the list has Hala's descendants except it has Halayudha for Hala, does not have Shobhana, and inserts Hari, Suvikrama, Vishvambhara, Balai, and Herambakari in his place before shori who is called Gauri instead, and omits Damodara; it also has Gadadhara instead of Gada; Note that Visho and Heramba do occur as cousins in the standar list) and the genealogy of the Savarna Roy Chowdhury family (like the previous except it mentions Vira Raghava and Hala as alias for Halayudha, a Gunai before Hari, Bishai instead of Vishvambhara, Heramba instead of Herambakari, Shauri instead of Gauri; it also has Gadadhara, Haladhara, Ayurama instead of Gada, Hala, Ayu, mentions Jiya as an alias of Shivai, and uses Purari instead of Purai; Note the presence of Gunakar Nayi in the standard list who could have been called Gunai) for yet other versions. See here for a tabular representation of the early part of this comparison. It is known from other genealogical traditions as well as the puranic king lists that this kind of error, especially the mistaking of cousins for direct ancestors is actually not very uncommon. A very different list is given in the genealogy of Bhatpara Bhattacharyas which I reproduce here.
Other people mentioned are vishveshvara kunda, hAsya gAGgulI, and keshava dAYI.
There is also the following incomplete one: hala  had a descendant (a different source gives Purari[14 above, but 18 there] -> Panchanan Gangopadhyay  alias Panchu Shakti Khan settled in Havelishahar alias Halisahar -> shambhupati  b. around 1500 -> Jiya Gangopadhyay  alias Kamadeva Brahmachari same as the following) kAmadeva  -> laksmIkAnta majumadAra rAYacaudhurI  who had gaurI, rAma, gopAla, vishveshvara, kRSNa, and mahAdeva. gaurI  -> shrImanta -> keshava -> santoSa  -> rAmalAla . brother of santoSa  -> rAjIvalocana rAYa  who was living in 1809. Descendants of santoSa  are called the sAvarNa caudhurIs from vaD.ISA. The sAvarNa rAYa caudhurIs who founded calcutta are descended from them and their web site mentions that jiYa gaGgopAdhyAYa (kAmadeva brahacArI) (1535/48-1620) married padmAvatI and had lakSmIkAnta (1570-1649) ->? vidyAdhara rAYa caudhurI.