There are plenty of anecdotal stories in the golfing world about how professional players tend to perform better after becoming fathers, with scientific studies actually showing that men also have hormonal changes after their partners give birth.
Becoming a father is a huge event in many men's lives, and can change how they approach things including their careers as they gain more focus following a drop in testosterone levels. Recently, Thomas Muller saw an upturn in his performances for both Bayern Munich and Germany, which actually tied in with a new arrival at the Muller household.
Muller's wife Lisa is an equestrian athlete, and the pair own many horses together. In early March, they welcomed a new foal into their lives and the 28-year-old celebrated that with one of his best performances of the season, scoring one and assisting two goals against Freiburg.
After the game, the jovial German pinpointed exactly where the performance had come from - the Mullers' new arrival!
"I was definitely geed up today," Muller told reports in the mixed zone. "My first foal of the season was born into the world last night. I feel as though I have become a father!"
Despite Jupp Heynckes heavily rotating the Bayern Munich starting XI to focus on winning another treble, Muller has played every minute since his new foal was born. That included an assist in Bayern's 3-1 second-leg win over Besiktas to send them into the Champions League quarter-finals and a goal and assist in the 6-0 rout of rivals Borussia Dortmund on Saturday.
Muller was also in stunning form for Germany during the international break, scoring the equaliser in the World Cup warm-up with Spain. The attacking midfielder picked up a pass from Sami Khedira in the centre of the park and then fired a thunderbolt from 35 yards which left David de Gea no chance. It was Muller's 38th goal in 90 appearances for his country, and came at exactly the right time as Joachim Low assesses his squad for Russia.
Before the Raumdeuter Renaissance of 2017-18, Muller appeared to be in decline. There were even murmurs in Munich that the boyhood Bayern fan could be on his way out of the Allianz Arena, with clubs in England eager to pounce on any instability.
After scoring 20 league goals in 2015-16, Muller travelled to France for the European Championships. There he was expected to lead his country to another major title having won the World Cup in 2014 and finished second to James Rodriguez in the race for the Golden Boot at that tournament.
Instead of glory, came the worse period of his career. He failed to find the net once during the tournament and even missed from the spot during the penalty shootout victory over Italy in the quarter-finals. He was anonymous against France in the semi-final as an Antoine Griezmann double put the hosts through.
Muller's return to Munich failed to see him turn things around. By March 2017, he had scored just one league goal despite plenty of opportunities under Carlo Ancelotti. Despite his unhappiness, Bayern refused to sell one of their most popular players, and he remained at the club as the transfer window closed.
At the start of the season, it looked as if the slump was continuing past the summer. Muller was benched for Bayern's second game of the season and then again for the Champions League clash with Anderlecht. By the end of September, he had scored just one goal. But two additions helped turn things around.
Firstly, a 3-0 defeat to PSG in Europe brought an end to Ancelotti's time in Bavaria and returned the retired Heynckes to the hotseat. The 72-year-old solved the dressing room crisis at the club and began to find the best in Muller once more, retaining him as the club's captain.
Then, Thomas and Lisa welcomed their new foal to further improve the forward's mood. Back was the entertaining extroverted character whose crazy antics spawned a thousand gifs on Bayern's official twitter accounts, while on the pitch the ramdeuter was reborn.
With Muller now back to his best and Bayern just one win away from the Bundesliga title, the new foal's 'father' could be welcoming another arrival before the end of the season: His second Champions League winner's medal.