This article discusses research on monkeys and seems to suggest that cocaine use by the mother during pregnancy has negative effects on brain development.
This article from parentsplace includes the following:
*Congenital anomalies occur in 7 to 26 percent of infants exposed to cocaine in utero. Cocaine can adversely affect embryonic and fetal development through interruption of uterine, placental, and fetal blood flow. Evidence of brain malformation or hemorrhage occurs in approximately 35 percent of infants exposed to cocaine in utero. Fetal cardiovascular abnormalities caused by maternal use of cocaine have been reported to occur in 4 to 40 percent of babies exposed to cocaine in utero. Defects or disruption of urinary and genital development have been found in 14 percent of infants exposed to cocaine n utero.
Following the birth, withdrawal symptoms are experienced in 31 percent of newborns exposed to cocaine in utero. These include seizures, depression, lethargy, feeding problems, hyperactive reflexes, vomiting, diarrhea, high- pitched cry, and restlessness. These symptoms may indicate damage to the central nervous system that may prevail throughout life.
On long-term follow-up, cocaine-exposed infants demonstrate significant cognitive and developmental delay.*
It looks like there is the possibility for all sorts of problems later in life. If they haven’t appeared in an obvious way, than your “friend” may have been lucky. However, there is concern that more subtle effects may occur, as this site suggests:
Many may recall that “crack babies,” or babies born to mothers who used cocaine while pregnant, were written off by many a decade ago as a lost generation. They were predicted to suffer from severe, irreversible damage, including reduced intelligence and social skills. It was later found that this was a gross exaggeration. Most crack-exposed babies appear to recover quite well. However, the fact that most of these children appear normal should not be over-interpreted as a positive sign. Using sophisticated technologies, scientists are now finding that exposure to cocaine during fetal development may lead to subtle, but significant, deficits later, especially with behaviors that are crucial to success in the classroom, such as blocking out distractions and concentrating for long periods of time.
As far as whether these children are more susceptible to addiction as adults: While my quick search didn’t turn up anything (and, as Broomstick notes, there are so many other factors that will have an effect) I think it makes sense that when babies are born addicted and have to go through withdrawal after birth, they must have a lifelong addiction already in place.