Do what you want with this. This is taken from Alfred Adler, one of the pioneers of modern Family Therapy and was more influential than Freud, though rarely spoke of, on Western Psychology. You can use this as a 'cold read' technique, but it is by no means pop psychology.

He spoke extensively on birth order and how it shapes personality - these are GENERAL guidelines, and may not always apply but often you'll be surprised as to their accuracy:

Eldest Children:
• An only child at first and the centre of interest & attention
• May feel “dethroned” or usurped by birth of second child; then may seek attention often on the positive side but if s/he feels overun, may become discouraged
• Often given responsibility and expected to set an example
• May feel power is a right, may become authoritarian or strict
Tends to be: steady, responsible, conforming, gets along well
with authority figures, high achiever, concerned with prestige
• Ambitious
• May develop a very competent behaviour pattern or become very discouraged
• Frequent typologies: has to be right, …perfect…superior

Second Child:
Tends to be: steady, responsible, conforming, gets along well
with authority figures, high achiever, concerned with prestige
• Ambitious
• May develop a very competent behaviour pattern or become very discouraged
• Frequent typologies: has to be right, …perfect…superior

Middle:
May feel uncertain of his/her place, neglected or unloved
Has neither the privileges of the oldest or the youngest
Often is more sociable
May be even tempered
Sensitive to injustices, unfairness
May feel “squeezed” but may also “squeeze” in the other direction to find a place
May have difficulty finding a place
Fewest acting out problems
Sociable
Greatest feeling of not belonging
Successful in team sports
Relates well to people
Competes in areas not attempted by oldest
Lowest need for intellectual achievement

Youngest:
May not feel taken seriously as he is the smallest
May lack self-reliance, and act helpless or want others to do for him/her
May remain a dependent “baby” into adulthood
May be allied with the oldest
May operate in overdrive and try to outdo or catch up to older sibs
May be pampered by parents or older siblings
May be attention seekers, family comedians
Never dethroned
(empirical studies show:
Greatest over-representation of psychiatric disorders
Most likely to be an alcoholic (increases with family size)
Empathetic
Similar characteristics of oldest in anxieties & fears if 5 years younger than next oldest, ( +5…)
Highest representation amongst writers
Most popular
Over represented in activities involving social interplay
)


ONLY:
“only game in town” and so may be center of attention, could be overprotected, pampered, self-centered
Parental anxieties may add to feelings of insecurity or lack of self-assurance
May feel incompetent if s/he compares self to adults
May have difficulty sharing, cooperating,
May gain approval or solicit sympathy by being shy or helpless
May become highly responsible
As a child may relate better to those who are older than to peers
May use adult language
Typology may be one of a “getter style” or “a doer style”
May fear loss of parents and fear being alone in the world
May be perfectionist or demanding
(empirical study of onlies: Highest need for achievement
Next to oldest, are the highest achievers
Most likely to go to college
Most behaviour problems
Lowest need for affiliation
Most need for affiliation under stress
Loners & lonely
Under represented among psychiatric clients
Act as onlies if more +7
)


So here, a good way to get some insight into the person's personality as well as how they fit into their families:)