Blair Logan, 27, will have to spend at least 20 years in prison for starting the fire in Milngavie, near Glasgow, in the early hours of New Year's Day in 2017.
Cameron Logan, 23, died while his girlfriend Rebecca Williams, 25, survived but was seriously injured.
They had returned to the family home from a New Year's Eve party at 4am and were sleeping on a camp bed in the living room when Blair Logan threw petrol over them and then lit it. The family dog, Gomez, also died in the blaze.
In July, Blair Logan — a supermarket worker — admitted murder, but during a police interview he claimed it was never his intention to hurt Miss Williams or kill his brother.
''It was not my intent to kill him but I did do it," he told detectives on January 13.
The High Court in Edinburgh heard Blair Logan killed his brother in retaliation after his brother had punched him earlier in the evening.
But the pair had a poisonous relationship and Blair Logan had clearly been planning the attack for months.
Statement from Rebecca Williams after Blair Logan is jailed for at least 20 years for murdering her boyfriend Cameron and trying to kill her pic.twitter.com/RqYHs5Pldc— Heart Scotland News (@HeartScotNews) August 11, 2017
A computer seized from his bedroom showed he had carried out internet searches on burns victims as early as October 2016.
His brother was cremated in Clydebank in February, with a Scottish flag draped over the coffin and a piper playing the anthem Highland Cathedral.
The court heard the brothers had a "hostile" relationship and had not spoken to each other since their grandmother's death in 2013.
A letter from their parents was read out in court.
"We find it extremely difficult to reconcile the Blair that they know with the Blair that caused Cameron's death," it said.
Sentencing him the judge, Lady Scott, said he had "acted with wicked recklessness."
The court heard Blair Logan was on the autistic spectrum, but there was no suggestion he had a mental disorder which negated his responsibility for the crime.
"Your motivation was malice. You had planned this attack for a considerable time," the judge told him.
Miss. Williams, a radio journalist, sustained "truly terrible injuries" from which she is still recovering.
"At the time Miss Williams was employed in her dream job in radio broadcasting — you have robbed her of her voice and her career, of her future with Cameron and of her confidence and sense of self-worth. She remains disfigured, impaired and in pain," said Lady Scott.
Blair Logan's lawyer, Shelagh McCall QC said he had shown genuine remorse.
In August last year Jazzie Watson, 20, stabbed to death his brother, Shamus McNama, 17, at the family home in Bristol when he objected to the way his sibling was talking to their mother.
But earlier this year North Korea's erratic leader, Kim Jong-un, was accused of ordering the killing of his half-brother, Kim Jong-nam, who was poisoned in Malaysia.
Fratricide is also a very old crime, which was first reported in the Bible when Cain killed Abel in a field.
According to the Book of Genesis, Cain became angry because his brother's offering to God — "fat portions from some of the firstborn of his flock" was looked on more favorably than his own —the "fruits of the soil."
But Cain was not jailed or executed — instead he was banished from Eden to live in the neighboring land of Nod, where he married and had a child, Enoch.