Dyson Allen, 19, was "out of his head" drunk and stoned when he lit hanging clothes in a bedroom wardrobe where four-year-old twins Holly and Ella Smith and their two-year-old brother Jordan were sleeping.
Their elder brother, Reece, 19, was overcome by fumes after he went upstairs at the family home in Freckleton, Lancashire, in an attempt to rescue them.
All four died from the effects of smoke inhalation from the blaze on January 7 last year.
Preston Crown Court heard the defendant had not grown out of a history of playing with fire when intoxicated, which he regarded as a "party trick".
Sentencing him to life imprisonment, Mr Justice Males said Allen had no motive to harm the children or anyone in the Smith family.
Mr Justice Males told him: "You have failed completely to recognise the dangerous nature of such conduct. I do not accept that there is now little or no risk because you have learned your lesson.
"If you were going to learn a lesson, it might have been expected that you would do so long ago when on one occasion you injured yourself. But you did not learn then and your games continued."