Well on enterprise, had a hint that the schism was during surack time because he said under the rapture wing..
Telepathy is genetics, so a few options are available as to why vulcans do and romulan don't.
1. The ones with the strong genetic traits didn't leave in the exodus. So there has never been a strong enough telepath breed on romulas.maybe something like a religious caste
2. Augmentation, again, the telepathy augments stayed.
3. Mutation. Geneticly were capable with one born like surak being rare. But after the nuclear wars. Radiation had an effect of more powerful telepathy being born. While romulan didn't have the radiation.
4. All vulcanoiods are capable but it takes a mental clarity and diciplne that the romulans are seldom capable of.
Telepathy is genetics, so a few options are available as to why vulcans do and romulan don't.
1. The ones with the strong genetic traits didn't leave in the exodus. So there has never been a strong enough telepath breed on romulas.maybe something like a religious caste
2. Augmentation, again, the telepathy augments stayed.
3. Mutation. Geneticly were capable with one born like surak being rare. But after the nuclear wars. Radiation had an effect of more powerful telepathy being born. While romulan didn't have the radiation.
4. All vulcanoiods are capable but it takes a mental clarity and diciplne that the romulans are seldom capable of.