The middle of the Ingebrigtsen trio, Filip, had gone into the race at a packed Olympic Stadium as favourite, the defending champion and current world bronze medallist.
The eldest, Henrik, had major championships experience, with a medal of each colour won in the last three European champs.
But that counted for nothing as Jakob, who turns 18 next month and is coached like his siblings by father Gjert, lived up to his billing as one to watch.
The trio insisted pre-race that family tactics would not be used, but they automatically stuck together at the back of the field early on.
Jakob then smoothly led his brothers to the head of the pack with two laps to go. When you thought one of his more experienced siblings might have then taken up the front running, the teenager surprised everyone by sticking to his inside line, kicking and just holding on through to the line.
"We're pretty much as good as each other," said the modest Jakob, who won in 3min 38.10sec.
The Ingebrigtsens' Norwegian teammate Karsten Warholm, having already won the 400m hurdles, had earlier seen his dreams of an audacious double go up in smoke.
- Thiam sees off 'KJT' -
Belgium's night was crowned, however, when Nafissatou Thiam added the European crown to her world and Olympic titles in a gripping heptathlon that went down to the wire with Britain's Katarina Johnson-Thompson.
Johnson-Thompson pushed as hard as she could, winning in 2:09.84, but Thiam stuck to the task at hand and came in just under 10 seconds behind.
It meant Thiam finished on 6,816 points, 57 ahead of the Briton (6,759), with Germany's Carolin Schaefer taking bronze (6602).
On a sour note, Schaefer's teammates Louisa Grauvogel and Mareike Arndt both withdrew from the finale after being involved in a car accident returning to their hotel following the javelin. They were treated in hospital, but suffered no serious injuries, according to the German team.
Double defending world champion Mariya Lasitskene, a Russian competing under a neutral flag, added another gold to her burgeoning collection with a best of 2.00m in the women's high jump.
She won on countback from Bulgaria's Mirela Demireva, Germany's Marie-Laurence Jungfleisch taking bronze (1.96).
In other women's events, Switzerland's Lea Sprunger was crowned 400m hurdles champion, Ukraine's Nataliya Pryshchepa won the 800m and Greek Paraskevi Papahristou's 14.60m was enough for gold in the triple jump.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)