The brothers play at Livingston Football Club – two of them in the first team – and Mrs Jacobs, 47, has been able to retire from shuttling them back and forth from training and matches.
With Keaghan, 20, and non-identical triplets Sheldon, Kyle and Devon, 18, old enough to drive, she can sit back and enjoy the games.
Mrs Jacobs said: "I would support them as far as they can go with football, as long as they're happy. They're all quite independent but we're a very tight-knit family.
"They do quite a lot on weekends and normally go together. But they have their arguments too."
Mrs Jacobs, a diabetes care specialist, added: "I've always tried to make them realistic – football is about being in the right place at the right time. Not everyone makes it big."
They share the same career aspirations, but each brother has his own back-up plan.
Keaghan is looking towards sports management, with Karl considering coaching. Sheldon is looking at business studies and possibly running his own company one day, and Devon wants a hands-on apprenticeship.
Keaghan has worked his way into the Third Division over the past couple of seasons and earlier this month Kyle joined him as the first of the triplets promoted to the senior game at the Almondvale club.
Both took the field on Saturday for the side's 1-1 home draw against Berwick Rangers.
Sheldon and Devon hope to soon join their brothers in the first team.
Devon said: "We have never lost a game playing together in the youth team. I play right back, Sheldon at left back, Kyle plays in midfield for the youths and Keaghan has been the over-age player in midfield as well.
"It would be fantastic if we could all turn out together for Livingston's first team and keep that run going."
The quartet first played together against Stenhousemuir in the SFL Youth match. Their record includes two successive Under-19 League titles and a Reserve League Cup Final.
Although born in South Africa – their father's employment brought them to Livingston in 1999 – all four said they dream of playing for Scotland.
Keaghan told The Co-operative Insurance League Insider: "We are close as brothers and close in age so we do most things together. We have always played football together.
"I look after them on the park and I am quite protective"
He added: "My dad's family are all from South Africa and mum is from Zimbabwe but our gran and grandad on mum's side are from Holland, so we could claim Dutch nationality as well.
"However, Scotland is all we have ever really known and where we did the majority of our schooling, so I would be delighted to be considered for Scotland at any level."
DYNAMIC DUOS ON THE FIELD
STIRLING-born Gary and Steven Caldwell, right, may play for different clubs but join forces for Scotland's national football squad.
Gary and Phil Neville both represent England when not playing for their respective Manchester United and Everton teams.
Other famous brotherly duos include Bobby and Jack Charlton, Rio and Anton Ferdinand, John and Paul Terry, Pippo and Simone Inzaghi, Shaun and Bradley Wright-Phillips, Frank and Ronald de Boer and Mark and Brian Stein.