It's no secret that Prince Louis is considered one of the more animated members of the royal family when it comes to royal outings. Though the occasions when the youngest child of the Prince and Princess of Wales is seen dancing in public, pulling funny faces, and playfully mocking his siblings can be seen as an insight into his budding personality, his familial role will also play into his ability to let loose, something he shares with a certain royal cousin. "Research tells us that birth order effects are subtle but consistent enough to spot patterns, especially when you also factor in gender mix," Swift Psychology's child and adolescent therapist, Laura Gwilt, tells us. "Youngest brothers, such as Louis or Lucas, tend to enjoy the relaxed parenting that comes with experience, and may use humour, charm, or creativity to make their mark," she adds, reflecting on Louis' cheeky likeness to his cousin Lucas Tindall, the youngest child of Zara and Mike Tindall's three-child brood. "With older siblings often close in age, they may also become skilled at finding their own niche within the group." Much like Louis, on the rare occasions that he is seen in public, Lucas, four, is shown displaying a sweet, rambunctious energy. How is Lucas Tindall like Prince Louis? In 2022, he made the most of some one-on-one time with big sister Mia, 11, as the two Tindall kids headed to the Festival of British Eventing near their home on the Gatcombe Park estate. Having pulled Mia's sunglasses off her face, Lucas enjoyed being tipped upside down as he walked on his hands. As the son of two sports stars (Zara is a professional equestrian and Mike previously played rugby for England), it's also no surprise that Lucas has a competitive side. He was seen cheering excitedly during the New Year's Day Racing Meet at Cheltenham Racecourse in January. How are Princess Charlotte and Lena Tindall similar? With George and Louis keeping royal fans entertained, their older sisters take on a different role in their three-child households. "Middle sisters, like Charlotte or Lena [Tindall], often develop a natural ability to mediate and adapt," Laura tells us. "Growing up between brothers can mean learning to move fluidly between different communication and play styles - something research links to strong social awareness and flexibility." Though Prince George and Mia Tindall both play the older sibling role, Laura suggests their approach to their younger siblings may differ. "Eldest sisters may mix leadership with nurturance, while eldest brothers may step naturally into a guiding role," she says – something I can certainly relate to as a big sister. "In families where the eldest is a brother, like George, studies suggest that leadership often blends with protectiveness, particularly towards younger sisters. Eldest brothers in public-facing families may also feel a pull to 'set the tone' for younger siblings, which can encourage confidence but bring a sense of responsibility early on."