From Rivalry to Resilience: 50 Facts About Siblings

In 1984, an 8-year-old girl diagnosed with sickle cell disease also developed acute myeloid leukemia. To combat the cancer, doctors administered chemotherapy and performed a stem cell transplant from her sibling. Remarkably, not only did this treatment successfully eradicate her cancer, but it also cured her sickle cell disease. Nearly three decades later, she remains free of both illnesses.

2. Quaternary twins refer to a rare occurrence where two babies are both cousins and genetic siblings. This phenomenon arises when two sets of identical sisters give birth to children with two identical twin brothers.

3. When parents display favoritism or intervene in sibling conflicts, it often leads to increased conflict among the siblings later in life. Additionally, such interference tends to decrease the likelihood of siblings collaborating in the care of aging parents.

4. Egypt enforces compulsory military service for males, but only if they have a brother. Conversely, if an individual has no siblings or only sisters, they are exempt from this requirement.

5. Cleopatra's lineage is marked by instances of incest. Evidence suggests that more than a dozen of her ancestors engaged in marriages with cousins or siblings, and it is probable that her own parents were siblings. In line with this familial tradition, Cleopatra eventually married both of her adolescent brothers.

Brent Gretzky, alongside his brother Wayne, holds the record for the highest number of NHL points scored by siblings, totaling 2,861 points. Brent personally contributed 4 points to this record.

7. Among the Akan people of Ghana, the second twin born is considered the elder sibling due to their perceived maturity in aiding their counterpart during birth.

8. The concept of a savior sibling pertains to a child conceived with the primary purpose of providing a stem cell transplant to a sibling afflicted with a fatal disease.

9. Research indicates that children often develop stronger bonds and derive greater satisfaction from their relationships with pets compared to their relationships with siblings, particularly if the pets are dogs.

10. Typically, firstborn children exhibit higher IQ levels compared to their siblings.

Baby sand tiger sharks exhibit cannibalistic behavior in the womb, with the largest and typically earliest embryo consuming its siblings until only two dominant embryos remain. Female sand tiger sharks often mate with multiple males, leading to intrauterine competition among the offspring for birth.

12. When identical twins reproduce with unrelated partners, their offspring become genetically similar cousins, akin to half-siblings in genetic relatedness.

13. China's single-child policy resulted in cohorts of individuals who had never encountered genetic siblings. For these children, understanding the concept of "sibling" proved challenging, exacerbated by the Chinese practice of using the term "brother" or "sister" when referring to cousins.

14. Mixed-race and ethnic minority individuals encounter difficulties in finding life-saving bone marrow and stem cell transplant matches due to the requirement for a partial genetic match. Direct siblings only have a 25% chance of matching.

15. Many individuals may unknowingly harbor another human within them as biological "chimeras," where the body absorbs an unborn sibling shortly after conception.

Humans possess the ability to identify blood relatives reliably through scent, distinguishing full siblings but not half-siblings or step-siblings. This is particularly evident in preadolescent children.

17. A study conducted at Ohio State University suggests that individuals with siblings are less likely to divorce compared to those without. Each additional sibling (up to seven) correlates with a two percent reduction in the likelihood of divorce.

18. Three-quarter siblings are individuals who share a genetic makeup midway between full siblings and half-siblings. This occurs when they have the same father but different mothers who are sisters, or the same mother but different fathers who are brothers.

19. Siblings born within a year of each other are colloquially referred to as "Irish Twins," though the term was formerly considered derogatory.

20. In 2009, identical twins Hassan and Abbas O. were implicated as suspects in a $6.8 million jewelry heist. Although DNA matching the twins was discovered, they were released due to the inability to ascertain which brother participated in the crime.

Wolfgang Mozart's sister, Maria Anna, shared his exceptional musical talent as a child prodigy. Regrettably, she was deprived of opportunities to showcase her abilities as an adult. Many of her compositions, including one admired by Wolfgang himself, have been lost, contributing to her relative obscurity.

22. Between 2006 and 2007, Poland witnessed a unique historical occurrence as identical twin brothers assumed the positions of prime minister and president simultaneously, marking the first instance of brothers holding both offices in a country's history.

23. During World War II, German siblings Adi and Rudolf Dassler collaborated in the production of sports shoes. Following a significant fallout, they parted ways, establishing rival firms, Adidas and Puma, respectively.

24. A notable South African marathon feat in 1999 involved twin brothers who, midway through the race, exchanged positions in a restroom. While one brother drove ahead, the other resumed running, ultimately finishing ninth and claiming a prize of R6000. A journalist astutely observed the discrepancy in their watch-wearing habits in different photographs.

25. The Wright brothers harbored a fear of flying together, fearing the possibility of both perishing in an accident and thereby halting their aviation research. They preferred to take turns flying to ensure at least one of them would survive to continue their pioneering work.