It's pretty clear to me that the UFP is a transhumanist society, but one that does so in a very limited set of ways.
Birth Defects and Genetic Defects
The lack of obvious defects is mentioned in a couple of places in the extended universe; it's less obvious in the canon universe, but we simply do not see serious birth defects or genetic defects. This implies quite strongly some form of genetic screening, and quite possibly in-utero corrections of known defects. In Voyager, we see that genetic screening and projection is in fact known and used when Torres is pregnant.
Likewise, they seem to be leery of cybernetics. LaForge is a double-whammy - a genetic defect not caught in utero, and a cybernetic fix for it.
We know that Picard has a synthetic heart - possibly grown from his own DNA, but having to be surgically replaced during the series.
The case of Dr. Bashir is a particular insight. It's not that he had genetic therapy... it is that he was boosted above human norms. In other words, had they been willing to have a son who was merely average, it's likely that the Federation would have used much smaller impact augmentations.
BASHIR: Oh, there's no stigma attached to success, Chief. After the treatments, I never looked back. But the truth is I'm a fraud.
O'BRIEN: You're not a fraud. I don't care what enhancements your parents may have had done. Genetic recoding can't give you ambition, or a personality, or compassion or any of the things that make a person truly human.
BASHIR: Starfleet Medical won't see it that way. DNA resequencing for any reason other than repairing serious birth defects is illegal. Any genetically enhanced human being is barred from serving in Starfleet or practising medicine.
O'BRIEN: I don't think there's been a case dealing with any of this in a hundred years. You can't be sure how they'll react.
BASHIR: Oh, I am sure. Once the truth comes out I'll be cashiered from the service. It's that simple.
(Episode 514: Doctor Bashir, I Presume)
Note the phrase "repairing serious birth defects"... we can see that birth defects are in fact allowed genetic resequencing.
Also, worth noting, is the other augments we get to see... and Bashir's own comments on them:
BASHIR: My parents managed to find a decent doctor to perform the DNA resequencing on me. These four weren't so lucky. They all suffered unintended side effects. By the time they were five or six, their parents were forced to come forward and admit that they'd broken the law so that their children could get treatment.
SISKO: Perhaps they waited too long.
BASHIR: There was nothing the doctors at the Institute could do for them. These cases are so rare there's no standard treatment.
Episode 533: Statistical Probabilities
Later in the same scene it's noted that the ban is specifically to discourage an augment arms-race. Further, later in that episode, we see that the other augments are brilliant, but erratic, and psychologically damaged; we don't know to what extent those damages go, but we can see that one of the issues is the same as Khan Noonian Singh... extreme arrogance.
Data, Lal and Lore
Data is, until established by courts otherwise, chattel property of Starfleet. Yes, he's essentially a happy slave; recall that he was denied permission to resign from Starfleet.
Likewise, Picard's reaction to Lal's activation is worth consideration. (Apologies for the long quote)
PICARD: I insist we do whatever we can to discourage the perception of this new android as a child. It is not a child. It is an invention, albeit an extraordinary one.
TROI: Why should biology rather than technology determine whether it is a child? Data has created an offspring. A new life out of his own being. To me, that suggests a child. If he wishes to call Lal his child, then who are we to argue?
PICARD: Well, if he must, but I fail to understand how a five foot android with heuristic learning systems and the strength of a ten men can be called a child.
TROI: You've never been a parent.
PICARD: What you have done will have serious ramifications. I am truly dismayed that you told no one of what you were doing.
DATA: I am sorry, Captain. I did not anticipate your objections. Do you wish me to deactivate Lal?
PICARD: It's a life, Data. It can't be activated and deactivated simply. This is a most stupendous undertaking. Have you any idea what will happen when Starfleet learns about this?
DATA: I have followed all of Starfleet regulations to the best of my ability. I expected they would be pleased.
PICARD: Well, you have taken on quite a responsibility, Data.
DATA: To prepare, I have scanned all available literature on parenting. There seems to be much confusion on this issue. One traditional doctrine insists, spare the rod and spoil the child, suggesting a punitive approach. While another more liberal attitude would allow the child enormous freedom.
DATA: And what Klingons do to their children
PICARD: Data! I'm not talking about parenting. I am talking about the extraordinary consequences of creating new life.
DATA: Does that not describe becoming a parent, sir?
PICARD: Data, you are seeking to achieve what only your own creator has been able to achieve. To make another functioning, sentient, android. To make another Data.
DATA: That is why I must attempt this, sir. I have observed that in most species, there is a primal instinct to perpetuate themselves. Until now, I have been the last of my kind. If I were to be damaged or destroyed, I would be lost forever. But if I am successful with the creation of Lal, my continuance is assured. I understand the risk, sir. and I am prepared to accept the responsibility.
TNG Episode 164: The Offspring
The general point being that Data, once declared a life form, creates another cybernetic life form, and it's controversial. Lal's legal status can be inferred to be dubious; further, being a different construction, she may or may not be fully regarded as the same "species" as Data. Likewise, Picard's initial description is "an invention, albeit an extraordinary one." Despite Data's years of service, Picard still sees Data as a device, not a person. It is interesting to note that Data rises in personhood through the series in the eyes of Picard.
quotes taken from http://www.chakoteya.net