The discussion chapter in Santhi Parva of Mahabaratha clearly makes us understand that at that time the Varnasramam was not there
The varnasramam arose like in all ancient socities by classing persons with the nature of the work they do
In our country it has developed in a lopsided way to Jaati
Now a days with the jaati culture being rampant a "Brahmin is born"But does he live to the rigid rules which govern a brahmin?
One of the late Acharyas either of Sringeri or Kanchi ( I do not exactly remember) had said in the present age a born brahmin to be a brahmin should earn his living out of his learning /studies and use his learning or study for his living.If he does Trade or moneylending or military activities he will never be a brahmin.Being a farmer can be condoned.
This is the gist of what I have read.
The mahabharat is really interesting.
Bhishma procured brides for kuru princes in all forms allowed to obtain brides. All the following forms of vivaha sanskaras are mentioned in the mahabharat:
a) Brahma vivaha (gifting daughter to a righteous man).
b) Asura vivaha (giving daughter in return for money or any form of shulka).
c) Rakshasa vivaha (kidnapping a woman, or obtaining wives as war booties by waging wars and conquering women).
d) Gandharva vivaha (man and woman choosing each other on their own, also includes the swayamvara ceremony).
e) Prajapatya Vivaha (gifting daughter away to the groom on a prelaid condition, to perform civic and religious duties together).
i have no idea if the following were mentioned in the Mahabharat, if they are please do let me know:
a) Paisacha vivaha (bride is drugged, intoxicated or made unconscious, union is consummated without her consent, and later a wedding ceremony takes place. Its the most condemned form of vivaha in all smrithis, yet considered legitimate).
b) Arsa vivaha (groom gives a pair of kine to bride's father to perform sacrifice and obtains bride - this also involve bride price but the diff is that the pair of kine is to be used for the purpose of sacrifice only).
c) Daiva vivaha (brides, right from princely patrons to slave people, were given away to priests in return for performing sacrifices or some ceremonies, as fees).
And suprisingly, despite considering the paisacha, rakshasa, asura and gandharva forms of wedding as aprasasta (unapproved) forms of marriage, they are still considered legitimate by all the smrithis.
I got all of this from the book, Hindu Sanskaras, by Rajbali Pandey, page 153-233.
And also read that (suprisingly), the old writers did not prohibit swagotra weddings, only the later day writers of smrithis did.
The word 'Gotra' in the vedas was rarely used and only used as a cow-pen (Vedic Index by Roth, with verses, pp.235, 236, 240).
The smrithis of Apastamba, Kausika, Baudhyayana originally did not prohibit swagotra marriages. Perhaps it still meant only cow or asset division at that time. They only avoid the same pravara.
However, it seems, there came a time when the dharmasutras became prominent (time period not clear, Rajbali Pandey only mentions it was the AD times), and even the law-books took a back seat. Swagotra and Sapinda weddings came to be prohibitted only from there on.
But even then, according to the book Hindu Sanskara by Rajbali Pandey, swagothra weddings were permitted beyond 7th generation of father and 5th generation of mother.
Rajbali Pandey says it was the later smrithis that declared swagotra weddings invalid and illegitimate. Its not clear why it was declared that way and how it happened. And its also not clear if the new writers over-ruled the laws of the old writers (Apastamba, Kausika, Baudhyayana). But there was something like a uniform blanket ban on swagotra weddings from this time period onwards. It looks very possible that the context and meaning of gotra also changed during this period. It no longer meant cow-pens and cow-divisions. This clearly was the AD times.
So, youngsters who have ended up falling in love with someone of the same gotra, maybe you can try to seek consent from the elders by citing the old smrithis of Apastamba, Kausika and Baudhyayana