Use the option -O and -osscan-guess also helps to discover OS information.
sudo -O 192.168.1.69
result:
Starting Nmap 6.40 ( http://nmap.org ) at 2016-07-08 00:24 BST Nmap scan report for peter-laptop-1 (192.168.1.69) Host is up (0.000037s latency). Not shown: 997 closed ports PORT STATE SERVICE 80/tcp open http 139/tcp open netbios-ssn 445/tcp open microsoft-ds No exact OS matches for host (If you know what OS is running on it, see http://nmap.org/submit/ ). TCP/IP fingerprint: OS:SCAN(V=6.40%E=4%D=7/8%OT=80%CT=1%CU=43939%PV=Y%DS=0%DC=L%G=Y%TM=577EE4B0 OS:%P=x86_64-pc-linux-gnu)SEQ(SP=106%GCD=1%ISR=107%TI=Z%CI=I%TS=8)SEQ(SP=10 OS:6%GCD=1%ISR=107%TI=Z%II=I%TS=8)OPS(O1=MFFD7ST11NW7%O2=MFFD7ST11NW7%O3=MF OS:FD7NNT11NW7%O4=MFFD7ST11NW7%O5=MFFD7ST11NW7%O6=MFFD7ST11)WIN(W1=AAAA%W2= OS:AAAA%W3=AAAA%W4=AAAA%W5=AAAA%W6=AAAA)ECN(R=Y%DF=Y%T=40%W=AAAA%O=MFFD7NNS OS:NW7%CC=Y%Q=)T1(R=Y%DF=Y%T=40%S=O%A=S+%F=AS%RD=0%Q=)T2(R=N)T3(R=N)T4(R=Y% OS:DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T5(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR% OS:O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T7(R=Y%DF=Y%T=40% OS:W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=Y%DF=N%T=40%IPL=164%UN=0%RIPL=G%RID=G% OS:RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=N%T=40%CD=S) Network Distance: 0 hops OS detection performed. Please report any incorrect results at http://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 18.26 seconds