8 out of 9 correct.
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@CinnamonSugar my 'birth order' experiences a mixed bag:
First year of life i was an 'only' and not only my parents but the neighbors in the Trailer Camp we lived in doted on me.
Then my 3 half sisters from Dad's first marriage came to live with us, after spending several years in a 'Children's Home' in NJ after being removed from their mother's custody. The eldest of them was in a different 'dorm' in separate building from younger two, which no doubt impacted their relationships with each other, especially since there were various types of abuse going on in the facility. The eldest resisted accepting my Mom, but she was protective of me from the start. i became not just the youngest, but 'the baby'. They ranged from 7 to 10 years older.
At age 10 my parents split up and Mom took me to NJ where both sides of extended family lived. After a brief attempted reconciliation over the holidays in winter of 56-57; Mom and i moved north and they divorced. i became an only, a latch-key kid. Loved the solitude except at holidays. But the oldest two of my sisters visited a couple of times a year and that was always a joy for me.
Mom remarried when i was about 13-14,but it was off/on for several years. When i was 16, Middle of Junior year HS, Mom got pregnant with my little brother. My 1st stepdad contributed money but he had wanted her to 'get rid of it' even tried to get to her to give the baby up for adoption to a rich couple he knew. But already in late 30s and having had more than one miscarriage she figured this was her last shot at another child of her own. (to her credit she loved my sisters, and was so fair to them that when the youngest of them told me at age 6 'You're not our real sister', i assumed i was adopted or something.) 1/1/63 i became a defacto 'eldest', the term these days is i was 'parentified' by the amount of responsibility i took on in regard to my baby brother. My life consisted mostly of school and caring for him while Mom worked, slept, or socialized outside our home. Just when i was finding my 'tribe' of openminded oddballs, the woman who had pushed me from earliest memory to socialize like a 'normal' child begrudged me time for myself, unless i was on babysitting jobs for others that she had arranged (and took 90% of my earnings then wondered why i was anxious to leave home.)
These things are interesting and backed by studies, but you have to understand that not all 'polls' or studies are conducted in ways that get at heart of any matter. How, where and of whom you ask the questions can influence how they respond.